...fatal error doom...

Browser stops working after starting uTorrent

2011-08-24T17:18:00.001-07:00

Short Description:

- Scientific Atlanta Illegal TCP header uTorrent
- uTorrent kills all other network traffic
- Firefox/IE7 slow to load webpages when uTorrent running
- Firefox: uTorrent slow browsing
- Browser stops working after starting uTorrent
- uTorrent blocks browser

I have a serious problem with utorrent...
It is a great program, the speed is amazing...
But !! After a while, my browser (Firefox, Opera) stops working, and any other program, except uTorrent, can't access the Internet anymore... The only way to get my browser working again is to reboot the computer !
I've tried to limit utorrent connection and speed allocation, but it doesn't change anything... Sooner or later, I can't surf anymore...
Has anyone experienced the same problem?
Have you got a solution?
Thanks for any help...

--------------- SOLUTION -----------------------

Check Firewall Event Logging, if you find Ilegal TCP Header then under Firewall Options uncheck IP Flood Detection.

Description	Count	Last Occurence
Illegal TCP header	1	Tue Oct 19 18:15:28 2010

Step by step:

1. Scientific Atlanta Setup

2. uncheck IP Flood Detection

Web.HttpRequestValidationException: A potentially dangerous Request ...

2011-07-19T07:43:00.000-07:00

Explanation from here

To prevent some script-injection attacks , with request validation turned off, you need to HTML encode the content of other controls on the form.

HTML encoding will automatically replace any ‘<’ or ‘>’ (together with several other symbols) with their corresponding HTML encoded representation. For example, ‘<’ is replaced by ‘<’ and ‘>’ is replaced by ‘>’.

Browsers use these special codes to display the ‘<’ or ‘>’ in the browser.

Content can be easily HTML-encoded on the server using the Server.HtmlEncode(string) API. Content can also be easily HTML-decoded, that is, reverted back to standard HTML using the Server.HtmlDecode(string) method.

Solution from here

A potentially dangerous Request.Form value was detected from the client – ASP.NET 4.0

Sunday, September 26, 2010 Posted by Suprotim Agarwal

If you happen to upgrade your .NET Framework to use the .NET 4.0 CLR's version of ASP.NET, then it helps keeping the ASP.NET 4.0 breaking changes document handy.

After the upgrade, most of the users using the Rich-text editors or textboxes to submit HTML data, encounter the following error “Exception type: System.Web.HttpRequestValidationException Exception message: A potentially dangerous Request.Form value was detected from the client“

Now we know about the request validation feature in ASP.NET that shields cross-site scripting (XSS) attacks to a certain level. However this level of security changes in ASP.NET 4.0 making it stricter in terms of request validation.

As given in the documentation “In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before theBeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request”

To fix this error, open your web.config and add the following setting inside as shown here

<system.web>
<httpRuntime requestValidationMode="2.0" />
... rest of your attributes come here

The disables validation for request data. Although this isn’t particularly a very good fix as it compromises security, I believe it’s the only quick hack available unless you want to float your own custom request validator.

Solution from HERE

A potentially dangerous Request.Form value was detected from the client (remarks="5678,

Description: Request Validation has detected a potentially dangerous client input value, and processing of the request has been aborted. This value may indicate an attempt to compromise the security of your application, such as a cross-site scripting attack. You can disable request validation by setting validateRequest=false in the Page directive or in the configuration section. However, it is strongly recommended that your application explicitly check all inputs in this case.

Exception Details: System.Web.HttpRequestValidationException: A potentially dangerous Request.Form value was detected from the client (remarks="5678,

Source Error:

An unhandled exception was generated during the execution of  the current web request. Information regarding the origin and location  of the exception can be identified using the exception stack trace  below.

Stack Trace:

[HttpRequestValidationException (0x80004005): A potentially dangerous Request.Form value was detected from the client (remarks="5678,

Version Information: Microsoft .NET Framework Version:2.0.50727.4016; ASP.NET Version:2.0.50727.4016

… which is nice by default, but in some situations where you want people to be able to enter markup of some kind you want to be able to disable this. There are several ways.

WebForms – Per Page

This is a matter of adding the ValidateRequest property to the page directive per page:

<%@ Page Language="c#" … ValidateRequest="false"%>

WebForms -Globally

To turn off validation (which is not recommended unless you need to and know the consequences) is doen by editing the Web.config file’s pages element and adding the validateRequest attribute as shown below:

   :   validateRequest="false" />   :

MVC – Action

To prevent this error in MVC you can do it per action by applying the ValidateInputAttribute to the action method.

[AcceptVerbs(HttpVerbs.Post)] [ValidateInput(false)] public ActionResult EditMyEntity(string newValue) {  : }

Visual Studio Shortcuts

2011-03-23T04:06:00.000-07:00

Visual Studio Command

Shortcut

Cursor

Cursor to previous position

Ctrl + Hyphen (-)

Cursor to next position

Ctrl + Shift + Hyphen (-)

Comment

Ctrl + K + C

Uncomment

Ctrl + K + U

Duplicate a line

Ctrl + C, Ctrl + V

Solution

Build the solution. You can even try F6

Ctrl + Shift + B

Start the application with Debugging

Start the application without Debugging

Ctrl + F5

Bookmarks

Add/Remove bookmark

Ctrl-k, Ctrl-K

Moves to the next bookmark in the document

Ctrl-K, Ctrl-N

Moves to the previous bookmark

Ctrl-K, Ctrl-P

Bookmarks windowCur

crtl-K, ctrl-W

IIS 7 restrict folder

2011-02-21T08:13:00.000-08:00

1. Create User and Group:
Control Panel/Administrative Tools/Computer Management/Local users and groups
- create User
- create Group

2. add user to group. Delete user from "users" group. Add group over specific folder. (properties/security tab)

3. Convert specific folder to Application in IIS.

4. In web config of just created application add your group and restrict anonymous user:

<?xml version="1.0" encoding="UTF-8"?>

<configuration>

    <system.web>

        <authentication mode="Windows" />

    </system.web>

   <system.webServer>

        <security>

            <authorization>

                <remove users="*" roles="" verbs="" />

                <add accessType="Deny" users="?" />

                <add accessType="Allow" roles="XMyGroup" />

            </authorization>

        </security>

   </system.webServer>

</configuration>

Visual Studio Debug, Release disappears in toolbar

2011-02-21T01:09:00.000-08:00

Solution configuration not showing up in Visual Studio 2010 or Visual Studio 2008

Go to Tools | Import Export Settings and reset your settings to the ones you need.

Could not load file or assembly: System.Web.Mvc, …

2011-02-01T08:20:00.000-08:00

Could not load file or assembly 'System.Web.Mvc, …

With the release of ASP.NET MVC Beta, the assemblies distributed with ASP.NET MVC are automatically installed into the GAC.

System.Web.Mvc
System.Web.Routing
System.Web.Abstractions

While developing an application locally, this isn’t a problem. But when you are ready to deploy your application to a hosting provider, this might well be a problem if the hoster does not have the ASP.NET MVC assemblies installed in the GAC.

Fortunately, ASP.NET MVC is still bin-deployable. If your hosting provider has ASP.NET 3.5 SP1 installed, then you’ll only need to include the MVC DLL. If your hosting provider is still on ASP.NET 3.5, then you’ll need to deploy all three. It turns out that it’s really easy to do so.

Also, ASP.NET MVC runs in Medium Trust, so it should work with most hosting providers’ Medium Trust policies. It’s always possible that a hosting provider customizes their Medium Trust policy to be draconian.

What I like to do is use the Publish feature of Visual Studio to publish to a local directory and then upload the files to my hosting provider. If your hosting provider supports FTP, you can often skip this intermediate step and publish directly to the FTP site.

The first thing I do in preparation is to go to my MVC web application project and expand the References node in the project tree. Select the aforementioned three assemblies and in the Properties dialog, set Copy Local to True.

Resource

XML to Class Generator

2011-01-25T05:45:00.000-08:00

1. Visual Studio 2008 -> Visual Studio Tools -> Visual Studio Command Prompt

2. Convert xml to xsd
D:\\test>xsd test.xml

3. Convert xsd to class
D:\\xsd.exe -c -l:c# -n:test test.xsd

4. Add new class to project.

root class hast to use [Serializable] atribute to deserialize

[Serializable]
[XmlRoot("response")]
public partial class TestKlasa

5. Deserialize


static TestKlasa Deserialize_Test(string response)
        {
            byte[] byteArray = Encoding.UTF8.GetBytes(response);
            MemoryStream responseStream = new MemoryStream(byteArray);

            try
            {
                XmlSerializer deserializer = new XmlSerializer(typeof(TestKlasa));
                return (TestKlasa )deserializer.Deserialize(responseStream);
            }
            catch (Exception e)
            { ;}
            finally
            {
                responseStream.Close();
            }

            return new TestKlasa();
        }
    }

Sources: here and here

visual studio change section to lowercase/uppercase

2011-01-12T00:51:00.000-08:00

Keyboard: CTRL + SHIFT + U (upper); CTRL + U (lower)
Menu: Edit -> Advanced -> Make Uppercase; Edit -> Advanced -> Make Lowercase

Win 7 Shortcut for Desktop Gadgets

2010-12-09T14:19:00.000-08:00

Win+G

Failed to access IIS metabase Error

2010-12-01T05:12:00.000-08:00

Add asp.net user(?)

Add framework version (i.e. 2 or 4)
c:/windows/microsoft.net/framework/v2.0.52727/aspnet_regiis -i

Exceptions with methods invoked by reflection

2010-07-08T02:58:00.000-07:00

If I use reflection to call a method via Invoke and that method throws an exception, the debugger stops on line where the method was called via reflection and not in the faulty method itself

How do I change this, and have the debugger stop on the line of code in error.

Solution:

Check the "Thrown" box for the particular exception -- the debugger will stop where the exception is thrown, before it's caught (and translated) by the Invoke layer.

In Visual Studio 2008, the Debug menu has an Exceptions... option.
When clicking this, it brings up the "Break when an exception is thrown" dialog.

Set page to center

2010-03-26T04:21:00.000-07:00

Solution:
Define width and set margin to 0.
width: 900px; margin: 0 auto;

Firefox keyboard shortcuts for Bookmarks

2010-03-12T02:47:00.000-08:00

1. Organize Bookmarks in Firefox
Bookmarks/Organize Bookmarks/More/Keyword: "Enter letters. Example: ag"

2. Open new Tab (Ctrl + T) and navigate to Address bar: Alt+D
- Search bar: Ctl + K

3. Enter your keyword. For Example - ag

Short if C# (C#: Conditional Shorthand)

2010-03-05T02:59:00.000-08:00

Explanation:
If statement is true use first value else use second value

Short if (Conditional Shorthand) Syntax:
(a==b) ? first_value : second_value ;

Short if Without Else ("Null" Conditional Shorthand):

(a==b) ?? value;

Example:
<asp:Literal EnableViewState="false" runat="server"
Text='<%# (Jezik=="it")? "N" + Convert.ToChar(176):GetResources("lblKapacitet") %>'></asp:Literal>

How to break out of a function in C#?

2009-11-01T14:07:00.000-08:00

return;

Detect Page Refresh In ASP.NET

2009-10-19T15:28:00.000-07:00

Source page is :
http://csharpdotnetfreak.blogspot.com/2009/09/detect-page-refresh-in-aspnet.html

If you have created a aspx page using C# and ASP.NET and have put a button on it. And in the Click event of this button if you are inserting some data in database , after click if user refresh the page than click event gets fired again resulting data insertion to database again, to stop events on the page getting fired on browser refresh we need to write bit of code to avoid it

1. Page Load


protected void Page_Load(object sender, EventArgs e)
        {
            //dio za provjeru jel se radi o refreshu
            if (IsPostBack == false)
            {
                Session["CheckRefresh"] = Server.UrlDecode(System.DateTime.Now.ToString());
            }
        }

2. Page_PreRender


protected void Page_PreRender(object sender, EventArgs e)
        {
            //dio za provjeru jel se radi o refreshu
            ViewState["CheckRefresh"] = Session["CheckRefresh"];
        }

3. Insert Click


protected void btnInsert_Click(object sender, EventArgs e)
        {
            //provjera jel se radi o refreshu i ako ne izvrsi ovu radnju
            if (Session["CheckRefresh"].ToString() == ViewState["CheckRefresh"].ToString())
            {
                //dio za provjeru jel se radi o refreshu
                Session["CheckRefresh"] = Server.UrlDecode(System.DateTime.Now.ToString());
               
                #region insert
            }
            GridView_Pronalazac.DataBind();
        }

How to refresh the current page in asp.net?

2009-10-18T15:20:00.000-07:00

Response.Redirect(Request.Url.ToString());

LinqToDataSource search over TextBox

2009-10-13T20:01:00.000-07:00

Smijes imat samo jedan textbox na stranici ako zelis da stvar radi preko entera. U protivnome upotrjebi Button. Na koji ne treba vezat nikakav "onClick" vec se koristi submit svojstvo botuna.

Show 0 instead of NULL

2009-10-02T04:21:00.000-07:00

SELECT

CASE WHEN TextField IS NULL THEN '0' END AS txt,
CASE WHEN numberField IS NULL THEN '0' END AS br

FROM dbo.TestTablica

How to retain the Values for GridView in Templatecontrol

2009-09-23T16:04:00.000-07:00

example:
asp :
In GridView : OnSelectedIndexChanged = "GridView_Species_SelectedIndexChanged"
In ItemTemplate: Use Label with id = "lblGenus_Item"

codebehind:
In GridView_Species_SelectedIndexChanged

// Get the currently selected row using the SelectedRow property.
GridViewRow row = GridView_Species.SelectedRow;
//sve value from label to the string
string genus = ((Label)row.Cells[2].FindControl("lblGenus_Item")).Text;

Bind value in DetailsView Insert Mode

2009-09-23T14:04:00.000-07:00

InsertItemTemplate can't bind data directly from asp. Use codebehind.
Example:
DetailsView_Species_DataBound (make shoure that DetailsView call for it)

if (DetailsView_Species.CurrentMode == DetailsViewMode.Insert)
{

Label Find_lblSpecies_Insert = (Label)DetailsView_Species.FindControl("lblSpecies_Insert");

Find_lblSpecies_Insert.Text = "aaaa";

}

Allow foreign key null value in SQL Server

2009-09-22T15:18:00.000-07:00

PROBLEM:
Allow in SQL SERVER a foreign key to have null values or values that can not be found in the related table (like 'zero')

SOLUTION:
It is not possible to insert null values in ViewTable mode. You need to use Right click on empty space in ViewTable mode, -> Pane -> SQL and use insert script.
(allow null values in Designe mode)

example
INSERT INTO SSS
(Literature_ID, Location_ID, Species_ID, Pronalazac_ID, Datum_ID)
VALUES (NULL, NULL, 11, NULL, NULL)

Multiple DataKeyNames in GridView

2009-09-21T16:16:00.000-07:00

string selectedDiggins = GridView1.DataKeys[GridView1.SelectedIndex].Values["Diggings"].ToString(); //selecting datakey by name

User Control - Adding Events

2009-09-21T15:59:00.000-07:00

1. define the events in code behind of user control
(Remember: To define an event you must use the event keyword with a delegate that represents the signature of the event. )

public event EventHandler SelectedIndexChanged;

2. Parameters

public string param_odabranaVrijednost
{
get { return odabranaVrijednost; }
//set { odabranaVrijednost = value; }
}

3.

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
string selectedID = GridView1.SelectedValue.ToString(); //first dataKey "Location_ID"
string selectedDiggins = GridView1.DataKeys[GridView.SelectedIndex].Values["Diggings"].ToString();
// finding dataKey by name

odabranaVrijednost = "Odabrani id je : " + selectedID.ToString();

if (SelectedIndexChanged != null)
{
SelectedIndexChanged(this, EventArgs.Empty);
}
}

4. Saving value in some text box inside page or control that uses user control

protected void SelectedIndexChanged(object sender, EventArgs e)
{
txtLokacija.Text = Lokacija1.param_odabranaVrijednost;
}

5. In designe mode .ascx or .aspx call eventhandler inside of used control

uc2:Lokacija ID="Lokacija1" runat="server" OnSelectedIndexChanged="SelectedIndexChanged" //moras napisat rucno OnSelectedIndexChanged jer je ovo kreirani event pa ga nema u inteli sensu

GridView Delete Item template: confirmation question before deleting.

2009-09-11T13:40:00.000-07:00

To make Delete button editable disable automatic delete and make it in ItemTemplate as LinkButton with command name "Delete".
To ask confirmation question use OnClientClick = "return confirm('some text ');"

To perform deleting after "deleteOnSubmit" you need to "SubmitChanges" and to see changes in gridview you need to "DataBind" gridview.

Firefoxa.exe Entry Point Not Found

2009-09-05T11:16:00.000-07:00

Problem:

I installed Firefox 3.5 and now each time at running time I get error message : "Firefox.exe - Entry Point Not Found"

Solution:

Go to your "C:\Windows\System32" dir
Look for this file:
DWMAPI.DLL
If it's there, either rename it to DWMAPI.DLL.OFF or move it out of the Windows dir to some backup folder elsewhere (don't delete it just yet, just incase).

How to get DataKey of GridView?

2009-08-25T15:00:00.000-07:00

Once you have specified DataKeyNames, you can retrieve the datakey for the
selected row by simply using - GridView1.SelectedValue

Example:

string selValue = GridView1.SelectedValue.ToString();

Zooming LinqToSql Table Diagram

2009-08-10T10:01:00.000-07:00

To zoom in or zoom out Linq To SQL Table Classes diagram press CTRL and scroll mousse button

Interface vs. Abstract ...nesrecnici po rodjenju

2009-07-24T05:13:00.000-07:00

[12:07:06] Cvjetko says: ako interface...podrazumijeva implementaciju "zajednicke funkcionalnosti ali RAZLICITE implementacije"

[12:07:15] Cvjetko says: i trazi pisanje koda...jer koda u interfaceu samom nema

[12:07:26] Cvjetko says: a astraktne klase...takodjer pod

[12:07:29] Cvjetko says: OBAVEZNO

[12:07:43] Cvjetko says: traze implementaciju (pisanje koda) jer isto tako koda nemaju...

[12:07:54] Cvjetko says: sto znaci...davanje zivota svim metodama...koje sadrze

[12:08:06] Cvjetko says: koja je SUSTINASKA razlika izmedju interfacea i abstraktne klase...

[12:08:14] Cvjetko says: ono na tragu...okvir i ...

[12:08:16] Luđa says: koliko sam skuzila apstraktne klase vec mogu imat kod

[12:08:20] Luđa says: ali to moram provjerit

[12:08:25] Luđa says: abstraktne klase se nadogradjuju

[12:08:49] Cvjetko says: dobro, taj detalj u sebi...nije bitan...to cu sad provjerit u sekund

[12:08:53] Cvjetko says: bitna mi je sustina...kuzis

[12:08:53] Luđa says: a sucelje ne mozes nadogradit

[12:09:01] Cvjetko says: kad primjenit interface kad abstraktnu klasu

[12:09:55] Luđa says: koliko ja kuzim...baznu klasu primjenjujes kad imas neka osnovna zajednicka svojstva koja se ipak u nasljedjivanju mogu ralikovat od vrste do vrste..ne znam moze li se radit overload.. ako da, onda je to to..

[12:10:03] Luđa says: a interface ti zapravo odredi maksimum do kojeg mozes ic

[12:10:07] Luđa says: i vise od toga ne mozes

[12:10:11] Cvjetko says: override se radi

[12:10:20] Luđa says: ne overrride nego overload

[12:10:29] Luđa says: ono sto mene buni

[12:10:30] Luđa says: je

[12:10:43] Luđa says: ako interface odredjuje maximum...sta se desava kad ih imas vise

[12:10:54] Luđa says: reagiraju kao skup pa je to zapravo set maximuma

[12:11:07] Cvjetko says: hm hm hm...

[12:11:21] Luđa says: ili imas jedno ogranicenje..a zelis ga ispravit...onda ubacis novi interface?

[12:11:43] Cvjetko says: ok, ajmo ovako, valjda cemo doc do toga

[12:11:44] Cvjetko says: cuj, ajmo to postavit ko ova zenica dobra: IShape ...dakle, "okvir"

[12:11:51] Cvjetko says: imas likove...

[12:11:56] Cvjetko says: krug, pravokutnik, trokut

[12:12:01] Cvjetko says: svaki se iscrtava drugacije

[12:12:09] Cvjetko says: interface je IShape , dakle okvir

[12:12:16] Cvjetko says: ima metodu, koja nema koda

[12:12:19] Cvjetko says: Draw

[12:12:40] Cvjetko says: primjena metode...moze i jest drugacija za svaki "element okvira"

[12:12:46] Cvjetko says: i to je interface

[12:12:52] Cvjetko says: ako ja zelim jos jedan interface

[12:12:56] Cvjetko says: on bi mogao bit...sta

[12:13:02] Cvjetko says: na primjeru ovome

[12:13:04] Cvjetko says: mozda....

[12:13:12] Cvjetko says: opseg

[12:13:19] Cvjetko says: svaki je drugaciji

[12:13:23] Luđa says: da..istina

[12:13:27] Cvjetko says: implementacija opsega kod svakog je drugacija

[12:13:31] Luđa says: jeste

[12:13:36] Cvjetko says: okvir je novi...Opseg

[12:13:38] Luđa says: a pitanje je

[12:13:45] Luđa says: asto tu isto ne upotrjebit abstraktnu klasu

[12:13:49] Cvjetko says: dakle,....novi interface je Okvir

[12:13:52] Luđa says: koja ima metodu koja se da overridat?

[12:13:56] Luđa says: koa je razlika?

[12:14:05] Cvjetko says: e o tome ti ja govorim zapravo

[12:14:19] Cvjetko says: sustinski razlog, zasto ne jedno a drugo ili obratno

[12:14:21] Cvjetko says: po meni

[12:14:47] Luđa says: zato sto

[12:14:49] Luđa says: evo zasto

[12:14:53] Luđa says: suuti

[12:14:54] Luđa says: evo zasto

[12:14:54] Cvjetko says: abstraktnu klasu koristis ako zelis primjenit isto, ali na drugaciji nacin...

[12:15:04] Luđa says: abstraktna klasa (ako moze imat koda)

[12:15:10] Luđa says: se nasljedjuje

[12:15:10] Cvjetko says: sekund

[12:15:11] Cvjetko says: stani

[12:15:15] Cvjetko says: zadrzi misao

[12:15:17] Cvjetko says: samo jedna recenica

[12:15:19] Luđa says: ne moogu

[12:15:23] Cvjetko says: kod abstraktne klase...

[12:15:29] Cvjetko says: obavezujes se!!!!

[12:15:36] Cvjetko says: preuzet sve metode abstraktne klase

[12:15:40] Cvjetko says: i IMPLEMENTIRAT ih

[12:15:43] Luđa says: aha

[12:15:44] Luđa says: ludja

[12:15:45] Cvjetko says: nema...pick and choose

[12:15:50] Luđa says: ok..onda slusaj

[12:15:51] Cvjetko says: moras uzet sve...

[12:15:53] Cvjetko says: nastavi

[12:16:01] Luđa says: a kod interfacea?

[12:16:07] Cvjetko says: isto tako

[12:16:10] Luđa says: ok..onda ovako

[12:16:17] Luđa says: abstraktna klasa se nasljedjuje

[12:16:20] Cvjetko says: istina

[12:16:23] Luđa says: ona u sebi moze imat vec dio koda

[12:16:27] Luđa says: metode sa kodom

[12:16:33] Luđa says: koje ti mozes i ne moras overridat

[12:16:35] Cvjetko says: jel se moze instancirat?

[12:16:38] Luđa says: ne

[12:16:46] Cvjetko says: ka ni interface...on ne moze bit objekt

[12:16:49] Luđa says: ok..slusaj

[12:17:02] Luđa says: znaci...ma prvo mi moramo provjerit moze li imat koda :))

[12:17:17] Cvjetko says: ajmo prvo se odlucit ili za jedno ili za drugo...

[12:17:21] Cvjetko says: ajmo od pocetka

[12:17:23] Cvjetko says: zasto

[12:17:27] Luđa says: zato jer ako moze

[12:17:28] Luđa says: to znaci

[12:17:39] Luđa says: da svaka durga klasa koja nasljedi apstraktnu klasu

[12:17:42] Luđa says: ima defoltne metode

[12:17:46] Luđa says: i definira samo one

[12:17:51] Luđa says: koje se razlikuju putem overrida

[12:17:52] Cvjetko says: i nasljedjuje odredjenu funkcionalnost...

[12:17:57] Luđa says: da.

[12:17:57] Cvjetko says: ok

[12:17:57] Luđa says: a interface nema niti jednu metodu

[12:18:01] Luđa says: i to znaci

[12:18:04] Cvjetko says: ok

[12:18:27] Luđa says: da ti mozes narpavit klasu koja izracunava broj kuteva u abstraktnoj klasi za kvadrat

[12:18:37] Luđa says: a ako bas koristis neki peterokut..onda overridas tu metodu

[12:18:50] Cvjetko says: zapravo je time mijenjas

[12:18:53] Luđa says: tocnije..ako ti je 90% toga u 4 kuta...onda ti to ustedi vrimena.

[12:18:59] Luđa says: ali idem vidit to sa kodom..

[12:19:03] Luđa says: meni nije jasno

[12:19:08] Luđa says: kad uzmeme nasljedjivanje interfacea

[12:19:13] Luđa says: ako je interface okvir

[12:19:19] Cvjetko says: e

[12:19:28] Luđa says: to bi znacilo da ne mozes imat metoda vise od onoga sto intrefcace nudi

[12:19:41] Luđa says: a ako nasljedim vise interfacea...onda od svakoga moras imat metode koje nudi

[12:19:48] Cvjetko says: da

[12:19:52] Luđa says: nije li prelazak na novi interface..gazenje okvira prvog interfacea.

[12:19:56] Cvjetko says: ne

[12:20:01] Cvjetko says: zasto bi bilo

[12:20:11] Cvjetko says: ako svaki interface daje odredjeni i samo odredjeni okvir

[12:20:15] Cvjetko says: samo se nadopunjuju

[12:20:25] Luđa says: znaci ne mozes imat manje ali mozes imat vise?

[12:20:30] Cvjetko says: kao....povrsina, opseg, elasticnost, bla bla

[12:20:39] Cvjetko says: mozes ih imat od 0 do koliko hoces

[12:20:50] Luđa says: mozes li ih imat manje nego ih ima u interfaceu

[12:20:53] Cvjetko says: ako ih mozes imat vise, a mozes, onda to znaci da jedan drugog NE gazi

[12:20:57] Cvjetko says: ako me logika sluzi

[12:21:01] Cvjetko says: jego NADOPUNJUJE

[12:21:04] Luđa says: aha

[12:21:27] Cvjetko says: prilikom implementacije interfacea

[12:21:43] Cvjetko says: broj metoda koje implementiras ovisi samo o broju "zacetih" metoda u samom interfaceu

[12:21:59] Cvjetko says: dakle...mozes ih imat i moras ih imat BAREM onoliko koliko ih ima u samom interfaceu

[12:22:05] Cvjetko says: a mozes li ih imat vise...to ne znam

[12:22:26] Cvjetko says: mislim da u abstraktnoj klasi...imas one koje moras implementirat i da mozes nanizat svojih koliko hoces

[12:22:37] Cvjetko says: aj vidi za kod u abstraknoj klasi

[12:22:55] Luđa says: abstrakne klase mogu imat apstraktne metode

[12:22:58] Luđa says: a one ne sadrze kod

[12:23:06] Luđa says: a mogu imat i obicne..ove valjda imaju kod.

[12:23:11] Cvjetko says: da

[12:23:14] Cvjetko says: slusaj dalje

[12:23:35] Luđa says: i mora implementirat sve abstraktne metode

[12:23:39] Cvjetko says: da

[12:23:48] Luđa says: sto znaci ako nisu abstraktni da ih mozes uobicajeno koristit?

[12:23:53] Cvjetko says: da

[12:24:02] Cvjetko says: ako su vidljive izvan...dakle, ako nisu private

[12:24:12] Luđa says: pitanje

[12:24:15] Cvjetko says: e

[12:24:23] Luđa says: moze li abstraktna klasa imat virtoalnu metodu za overridanje

[12:24:48] Luđa says: ili su sve metode u abstraktnoj klasi automatski dopustee za overrride

[12:24:49] Cvjetko says: to spada u "obicne" metode

[12:24:52] Cvjetko says: po meni ...moze

[12:25:00] Luđa says: obicne ne mozes overridat

[12:25:07] Cvjetko says: mozes ako su virtualne

[12:25:13] Luđa says: pa onda nisu obicne!

[12:25:23] Cvjetko says: public virtual string ()

[12:25:29] Luđa says: udrit cu te

[12:25:31] Cvjetko says: al su u tom smislu obicne jer nisu abstraktne

[12:25:44] Cvjetko says: jel ima keyword abstract za metodu...

[12:25:46] Cvjetko says: ima jel da?

[12:25:50] Luđa says: ovo je super

[12:25:53] Luđa says: slusam vas oboje od jednom

[12:26:06] Luđa says: mene zanima

[12:26:12] Cvjetko says: svaka metoda je obicna ako nije abstraktna, po meni...

[12:26:15] Cvjetko says: prema tome...moze

[12:26:22] Luđa says: majko moja

[12:26:26] Cvjetko says: ko meni brani da stavim virtualnu metodu u abstraktnu klasu

[12:26:37] Luđa says: pa ok

[12:26:42] Luđa says: onda je abstraktna klasa

[12:26:43] Cvjetko says: mozda grijesim, ali to je moje misljenje...

[12:26:45] Cvjetko says: e

[12:26:48] Luđa says: zapravo

[12:26:54] Cvjetko says: nadklasa obicne klase...

[12:26:56] Luđa says: temelj sa elementima okvira

[12:26:56] Cvjetko says: :)

[12:27:10] Luđa says: a ovaj jeb. interface je samo okvir

[12:27:20] Cvjetko says: hmmmm...mislim da abstraktna klasa je supervojnik

[12:27:28] Luđa says: a ja mislim da je kiseli kupus

[12:27:54] Cvjetko says: cek

[12:28:31] Cvjetko says: moze li abstraktna klasa naslijedit interface?

[12:28:48] Luđa says: zanimljivog li pitanja :)

[12:28:49] Cvjetko says: public abstract class Krug:Okvir

[12:28:57] Luđa says: mislis IOkvir :)

[12:29:04] Luđa says: ne znam

[12:29:27] Cvjetko says: ocu pitat predraga?

[12:29:41] Cvjetko says: ajmo prvo opalit to pitanje na google

[12:29:53] Luđa says: to i radim :)

[12:30:37] Luđa says: http://mindprod.com/jgloss/interfacevsabstract.html

[12:30:59] Cvjetko says: hahhah

[12:30:59] Cvjetko says: aj sad ko ce brze citat

[12:31:11] Luđa says: ne..nego..mozda tomo to i nije najbolje objasnija

[12:31:22] Luđa says: a nama je bas bilo ludja objasnjenje pa smo ga tili na silu zadrzat

[12:31:24] Cvjetko says: mozda

[12:31:25] Cvjetko says: :)

[12:31:26] Cvjetko says: When should you use an abstract class, when an interface, when both? Interfaces and abstract classes seem superficially to provide almost the same capability. How do you decide which to use?

[12:34:26] Luđa says: http://jelle.druyts.net/CommentView.aspx?guid=fe5e801e-71e5-474e-8235-01b2ad14ff68

[12:38:01] Luđa says: znas kako ti ja gledam interfaceve i bazne klase

[12:38:06] Luđa says: da skratimo ovo mucenje

[12:38:15] Cvjetko says: bazne klase=abstraktne?

[12:38:39] Luđa says: interface koristimo kad npr zelimo uvest novu klasu a da odgovara standardima vec postojece strukture

[12:38:40] Luđa says: npr.

[12:38:58] Luđa says: Imas zivotinje sa propertijima : oci, noge, ...

[12:39:06] Luđa says: i sad zelis uvest kokos

[12:39:24] Luđa says: i klasu koju kreiras o kokosi isto nabrajas oci, noge...bla bla

[12:39:36] Cvjetko says: s tim da je kokos novi interface...?

[12:39:51] Luđa says: ne..s time da kokos koristi taj interface zivotinja

[12:39:55] Luđa says: znaci

[12:40:01] Luđa says: Kokos:IZivotinja

[12:40:08] Cvjetko says: ok

[12:40:25] Luđa says: a bazna klasa bi bila

[12:40:54] Luđa says: tj. se koristi u izgradnji

[12:41:03] Luđa says: dakle prije nego uposlis te druge zivotinje preko interfacea

[12:41:09] Luđa says: ti zelis definirat sta svaka zivotinja ima

[12:41:20] Luđa says: + neke moguce varijacije zbog ceka koristis abstrakne metode

[12:41:31] Cvjetko says: ok, definiras bazičnu funkcionalnost---

[12:41:34] Cvjetko says: u baznoj klasi

[12:41:38] Luđa says: e

[12:41:57] Luđa says: sad bi nam jos samo tribalo 10064 primjera

[12:42:01] Luđa says: da nam to sidne u prirodnom obliku.

[12:43:25] Cvjetko says: When you implement the interface, you start from scratch without any default implementation. You have to obtain your tools from other classes; nothing comes with the interface other than a few constants. This gives you freedom to implement a radically different internal design.

[12:43:46] Cvjetko says: The abstract class author has imposed structure on you. Depending on the cleverness of the author of the abstract class, this may be good or bad.

[12:44:01] Cvjetko says: You must use the abstract class as-is for the code base, with all its attendant baggage, good or bad.

[12:44:20] Cvjetko says: dakle...kad definiras abstraktnu klasu, sa svim njenim sadrzajem...koristis je KAKO-JE

[12:44:39] Cvjetko says: interface...ti daje slobodu da napravis nesto sasvim drugacije...ne ovisi o bazi, niti malo

[12:44:49] Luđa says: ali ona moze imat abstrakne clanove koji se daju modificirat..sto je obiljezje sucelja.

[12:45:02] Luđa says: interface ti daje da napravis sucelje ka sta je to osnovno

[12:45:23] Luđa says: valjda kako jednom prilikom nebi dvi zivotinje bile toliko razlicito definirane da se ne mogu lagano koristit u medjukodu

[12:45:25] Cvjetko says: u tom smislu...interface, sam za sebe, jeste okvir, unutar kojeg plivas...kako hoces...abstraktna klasa isto je okvir ali sa definiranim pravilima ponasanja...koja mozes nadogradjivat

[12:45:42] Luđa says: a recimo da je to -to

[12:45:50] Luđa says: iako ...koji je smisao svega toga u konacnici?

[12:45:58] Cvjetko says: sloboda djelovanja valjda

[12:46:18] Cvjetko says: moram vidit ovo sa nasljedjivanjem...abstraktnih klasa

[12:46:34] Luđa says: to ti je ja mislim za ovaj biznis layer

[12:46:46] Luđa says: ili mi lici na njega...za jnega

[12:46:48] Luđa says: dakle

[12:46:51] Cvjetko says: kako mislis

[12:47:17] Luđa says: evo ovako nekako

[12:47:25] Cvjetko says: u business logic layeru...mos mijenjat temeljnu funkcionalnost...to mislis?

[12:47:34] Luđa says: imas metodu koja poziva metodu koja za parametar ima objekt

[12:47:40] Luđa says: ovdi

[12:47:47] Cvjetko says: ok

[12:47:54] Luđa says: dobijes prakticki klasu sa definiranim metodama koje su uvik iste

[12:48:01] Cvjetko says: ok

[12:48:07] Luđa says: i zapravo mozes biznis logicu prosljedjivat tu klasu tj. njen objekt

[12:48:10] Luđa says: za parametar

[12:48:11] Luđa says: dakle

[12:48:14] Cvjetko says: ok

[12:48:24] Luđa says: ako imas pasa, macku i konja koji svi imaju istu strukturu

[12:48:34] Luđa says: onda objekt macke sa zajednickim parametrom oci

[12:48:41] Luđa says: mozes prosljedit metodi

[12:48:50] Luđa says: koja npr. oci boja u odredjenom momentu u crveno

[12:48:57] Luđa says: npr

[12:49:38] Luđa says: bojanje_ociju(Zivotinja aa) { aa.Oci(rozo)}

[12:49:50] Luđa says: a na drugu stranu za parametar prosljedjujes objekt Pas

[12:49:57] Luđa says: koji ima metodu oci

[12:50:25] Luđa says: i u momentu kad izmetode bojanje_ociju

[12:50:37] Luđa says: pozoves prosljedjeni parametar aa.Oci sto je jednako Pas.Oci

[12:50:40] Luđa says: pas ce imat roze oci

[12:50:42] Luđa says: kuzis

[13:03:33] Cvjetko says: http://www.index.hr/vijesti/clanak/nagibni-vlak-iskocio-iz-tracnica-ima-mrtvih/443114.aspx

[13:06:37] Luđa says: evo mog primjera zasto ce nam jeb. interfaceovi

[13:07:01] Cvjetko says: If the various objects are all of-a-kind, and share a common state and behavior, then tend towards a common base class. If all they share is a set of method signatures, then tend towards an interface.

[13:07:15] Luđa says: ma ja razumin tooo

[13:07:21] Luđa says: ali moje pitanje je ZAŠTO

[13:07:24] Luđa says: shvacas

[13:07:28] Cvjetko says: ajde daj primjer

[13:07:31] Luđa says: kako ce to tebi ikad pomoc

[13:07:36] Cvjetko says: nece nikad

[13:07:38] Luđa says: Na primjer

[13:07:38] Cvjetko says: :)

[13:08:11] Luđa says: izgubila sam ga :)

[13:08:36] Luđa says: evo

[13:08:40] Luđa says: imaš klase kistova

[13:08:42] Luđa says: npr.

[13:09:05] Luđa says: svaki kist ima svoje baze, svoju debljinu, svoju jacinu pritiska i bla bla

[13:09:14] Luđa says: imas interface koji definira njihova zajednicka svojstva

[13:09:24] Luđa says: Debljina kista, Pritisak, Set boja

[13:09:37] Cvjetko says: ok, isti signature

[13:09:41] Luđa says: i imas trecu najudaljeniju klasu koja je zapravo tools

[13:09:56] Luđa says: ta klasa u sebi instancira sve te druge klase tj. tipove kistova

[13:10:06] Luđa says: i kad ti radis konkrento sa aplikacijom

[13:10:14] Luđa says: ili kodom

[13:10:21] Luđa says: imas mogucnost da u odredjenom momentu

[13:10:34] Luđa says: npr Kist1.Boja(Crvena)

[13:10:40] Luđa says: Kist2.Boja(zelena)

[13:10:57] Luđa says: i to sve unutar te klase Tools

[13:11:05] Luđa says: Kad nebi bilo interfacea

[13:11:08] Luđa says: onda bi se moglo dogodit

[13:11:17] Luđa says: da npr. dva tima kreiraju klase

[13:11:34] Luđa says: i jedan tim napravi Kist1 sa metodom Boja ali u nju prosljedjuje 4 parametra

[13:11:47] Luđa says: a tim dva napravi Kist2 sa metodom BojeBojice

[13:11:56] Luđa says: i sad ti koji pises tools

[13:12:06] Luđa says: moras za svaku klasu proucavat sta im znaci koja metoda

[13:12:10] Luđa says: Osim toga

[13:12:17] Luđa says: interfacei odredjuju i broj parametara

[13:12:19] Luđa says: sto znaci

[13:12:43] Luđa says: da ako tim 1 i tim 2 naprave dvi kist 1 i kist 2 koji cak i imaju metodu istog imena

[13:12:57] Luđa says: zamisli da metoda kista 1 prima 4 parametra a metoda kista 2 1 parametar

[13:13:04] Luđa says: opet je nahebao ovaj koji pise Tools klasu

[13:13:12] Luđa says: jer se mora bakcat sa razlicitim rjesenjima za istu stvar

[13:13:24] Cvjetko says: jasno mi je to sto govoris

[13:13:27] Cvjetko says: logika iza toga

[13:13:33] Cvjetko says: nadam se da je to ...odprilike to

[13:13:44] Luđa says: ono

[13:13:46] Cvjetko says: nemamo nikoga da nam to potvrdi

[13:13:46] Luđa says: da se ne desi

[13:13:56] Luđa says: da treci jadnik mora skupljat mozdane isprtke dvaju timova

[13:14:10] Luđa says: mozemo tomu sutra na kavi ..ako ne zaboravimo ovu teoriju :)

[13:14:15] Cvjetko says: sutra je subota

[13:14:48] Luđa says: mislim da je to to..

[13:14:54] Luđa says: a znacenje mozes prosirit i na kod

[13:15:11] Luđa says: zamisli da postoji neki collection koji skuplja objekte i automatski ih puni bojom

[13:15:31] Luđa says: onda mu zapravo i treba identican set parametara za svaki objekt ciju metodu zove.

[13:15:49] Luđa says: jer ne mozes automatiziranom kodu rec..aj mlao prouci sta radi koja metoda kojeg objekta.

[13:16:00] Luđa says: zapravo

[13:16:05] Luđa says: ako se dovoljno daleko odmaknes

[13:16:07] Luđa says: mozes vidit

[13:16:09] Luđa says: da se time

[13:16:14] Luđa says: tim interfaceovima

[13:16:25] Luđa says: klase pretvaraju u pripremljene vrjednosti za niz

[13:16:57] Luđa says: znaci...daje im se struktura podatka kojoj se onda moze pristupit po nekom indexu iz nekog colectiona

[13:17:08] Luđa says: i na dobivenu vrjednost automatski zalipetat predpostavljeni kod

[13:17:21] Luđa says: jer se ocekuje da je struktura niza objekata identicnog seta metoda.

[13:17:35] Cvjetko says: dakle, isti signature

[13:17:38] Cvjetko says: o tome govoris

[13:17:40] Luđa says: i iste metode

[13:17:56] Luđa says: misim..isti nazivi metoda

[13:18:10] Cvjetko says: sve je to super...idem potrazit na jebenom netu, doslovno, zdravo seljacki primjer...al ono, iza totalne idiote

[13:18:21] Luđa says: fuck you

[13:18:31] Cvjetko says: jos uvijek smo u domeni...teorije, bez definitivne potvrde

[13:18:38] Cvjetko says: i need SOLID PROOF

[13:24:18] Luđa says: iako ja mislim

[13:24:22] Luđa says: kad ti dobijes to radit

[13:24:31] Luđa says: nista te od ovih pitanja nece bunit

[13:24:37] Luđa says: i imat ces slatku djecicu

[13:24:40] Luđa says: i zenu zvana Bebica

[13:24:51] Cvjetko says: ajmo pitat predraga

[13:24:57] Cvjetko says: na konkretnom primjeru u autoscoutu

[13:25:05] Cvjetko says: otisa je...mogli smo sa njim u konfu

[13:26:05] Luđa says: a ne mislim da on to na primjeru as-a moze dobro objasnit

[13:26:11] Luđa says: i da bi u krajnjoj liniji potrajalo.

[13:26:24] Cvjetko says: a po tome nista se ne smi pitat :)

[13:26:28] Cvjetko says: al dobro, necem

[13:26:35] Luđa says: pitaj ako mislis da ce ti pomoc

[13:26:35] Cvjetko says: idjem nac konkretan primjer

[13:27:17] Cvjetko says: http://geekswithblogs.net/mahesh/archive/2006/07/05/84120.aspx

[13:31:20] Luđa says: ma OK ali i dalje ti nitko ne odgovara na pitanje

[13:31:28] Luđa says: koji ce ti K... to sve skupa

[13:31:46] Luđa says: tako da je moja teorija ludja i primjenjuje se dalje dok se ne dokaze da je kriva :)

[13:32:05] Luđa says: znas sta je zaheb sa ovim jeb. interfaceima i abstraktnim klasama

[13:32:10] Cvjetko says: e

[13:32:17] Luđa says: to sto one zapravo nikad ne zazive

[13:32:19] Luđa says: ka neke opne su

[13:32:28] Luđa says: nemas ih konkretno

[13:32:30] Luđa says: ne punis ih

[13:32:34] Luđa says: ne upravljas njima

[13:32:37] Luđa says: ne provlacis ih

[13:32:43] Luđa says: tj...neema ih

[13:32:51] Luđa says: aj aj..abstrakna i ima neki pticji isprdak

[13:33:00] Luđa says: ali interface je zapravo ko neko sveto pismo

[13:33:05] Luđa says: ili bozje zapovidi

[13:33:26] Luđa says: ti zivis svoj zivot sa svojim mukama...al se moras prilagodit bozjim zapovidima...pa se snadji druze.

[13:33:31] Luđa says: a ako ti je bas toliko tesko

[13:33:41] Luđa says: onda uz svog boga uvedes jos i muhameda da ti malo proveca prava

[13:33:48] Luđa says: to je slucaj kad npr. uzimas dva interfacea

[13:34:01] Luđa says: al onda ti i taj natovari svoje setove metoda kojima se moras pokoravat.

[13:34:20] Luđa says: to je to :)

[13:34:29] Cvjetko says: al mozemo se igrat boga i napisat svoj

[13:34:41] Luđa says: sta..intreface?

[13:34:42] Cvjetko says: da

[13:34:45] Cvjetko says: neovisno o postojecim

[13:34:46] Luđa says: al to i je bit

[13:34:51] Luđa says: zamisli da ti radis u vise timova

[13:34:58] Luđa says: i imate bazni projekt za kojeg pisete klase

[13:35:00] Luđa says: bas taj primjer

[13:35:17] Luđa says: imas zadane interfaceove i svoj projekt di tribas napravit te kistove

[13:35:40] Luđa says: ti interfaceovi ti govore sta smis upotrjebit ako zelis da tvoja klasa bude primjenjiva u toolsima

[13:35:50] Luđa says: mozes ti svojoj klasi nadodat jos sto propertija, metoda

[13:35:58] Luđa says: ali ovaj tim sto radi toolse se nece bavit time

[13:36:06] Luđa says: njih samo zanima njihov standardni izgled

[13:36:23] Luđa says: sta bi bilo kad bi u microsoftu svaki programer pisa svoje ideje i to u obliku koda

[13:36:59] Luđa says: bi trebao bit jos jedan firma koja se bavi interpretacijom njihovih ideja i na kraju opet, sklapanjem u medjusobno kompatibilne djelove

[13:37:18] Cvjetko says: ok

[13:37:35] Cvjetko says: ajmo rec da su interfacei "ludjacka kosulja"

[13:37:37] Cvjetko says: :)

[13:37:44] Luđa says: svidja mi se

[13:37:47] Cvjetko says: eto

[13:37:50] Luđa says: ludja

[13:37:56] Luđa says: ti bi se trza...al neeces

[13:38:01] Cvjetko says: ne mozem

[13:38:03] Cvjetko says: sputan sam jadan

[13:38:05] Luđa says: e

[13:38:12] Luđa says: supac :)

[13:38:22] Luđa says: ocemo to sutra rec njima sta smo zakljucili :D

[13:38:29] Luđa says: mi smo svi u ludjackim kosuljama :)

[13:38:29] Cvjetko says: hocemo, u ponedjeljak

[13:38:46] Cvjetko says: toster upotrijebi za ispec kruv a peglo mte lupim u glavu za svaki slucaj

[13:38:58] Cvjetko says: poveznica je...obiteljsko nasilje

[13:39:02] Luđa says: hahahahaa

[13:39:09] Cvjetko says: obiteljsko nasilje je okvir

[13:39:11] Luđa says: samo sto nema socijalne sluzbe

[13:39:25] Luđa says: obiteljsko nasilje je sve skupa

[13:39:33] Luđa says: prvo te naprave ...to je abstraktna klasa :D

[13:39:45] Luđa says: onda te jos malo odgajaju..i to je abstraktno

[13:39:54] Cvjetko says: jer je moras nadopunit, ako uzmes da je samo zacece abstraktna metoda

[13:40:03] Luđa says: eee

[13:40:04] Luđa says: da

[13:40:14] Luđa says: noc u kojoj su se zvaknuli

[13:40:19] Luđa says: je pocetak pisanja klase :D

[13:40:23] Cvjetko says: :)

[13:40:32] Luđa says: a ako su to morali cinit vise puta

[13:40:39] Luđa says: onda su stvarno losi programeri

[13:42:11] Cvjetko says: a ako na pubertet gledas kao na fazu realizacije te abstraktne metode zaceca...u tom smislu, ako u samom zacecu mozes kao Simonica i Ante uvjerit sebe da ce nusproizvod bit pametan na mamu, onda koristis abstraknu metodu...ako bude sansa da dijete uspije u zivotu i odstupa od bolesnih roditelja...dakle, periferno se razvija drugacije od svoje maticne baze...onda korisitmo interface

[13:42:50] Luđa says: mogu li ovo objavit na fatalerrordoom-u? :)

[13:42:59] Cvjetko says: naravski...uz moje ime

[13:43:02] Cvjetko says: ;)

[13:43:06] Luđa says: nemaj zime..i tvoju sliku

[13:43:13] Luđa says: zapravo

[13:43:19] Luđa says: mogla bi cili ovaj razgovr objavit :)

[13:43:27] Luđa says: i ocu..da znas..to je moj blog!

[13:43:41] Cvjetko says: ti si tu bog, nemoj past na tjeme

[13:43:50] Luđa says: koji je naslov?

LinqDataSource exceptions

2009-07-02T06:51:00.000-07:00

When working with the LinqDataSource, you may get the exceptions listed below.

1. Operator '==' incompatible with operand types 'Int32' and 'Object'

2. Operator '==' incompatible with operand types 'Guid' and 'String'

Source of this text: here

How to set background color of textbox in C#

2009-06-30T03:51:00.000-07:00

How to set background color of textbox in c#

Codebehind:

using System.Drawing;

txtRokDatum.BackColor = Color.White;

AjaxToolbox: AccordionPane Button onClick does not working

2009-06-19T07:03:00.000-07:00

PROBLEM:
I'm ussing couple of accordion panes and each one is calling usercontroll. Each ussercontrol has button. If I click on bottun, debuger never goes into onClick function.

SOLUTION:
If there is nothing to validate change button property "CausesValidation" to False

Ajax Toolkit: Accordion SelectedIndex problem after refresh in firefox

2009-06-18T06:46:00.000-07:00

PROBLEM:

If I use SelectedIndex In Accordion control after refresh in firefox the context of needed pane will be showed. How to fix this?

SOLUTION:

Turn Off the Autocompletion Feature.

Exapmle:
form id="form1" runat="server" enableviewstate="True" autocomplete="off"

How to call Insert Stored Procedure with Output parameter in C#

2009-06-02T05:43:00.000-07:00

1 . Stored procedure for Inserting with Output parameter:


ALTER PROCEDURE [dbo].[Insert_Narucitelj]

@NAR_ID_Narucitelja int Output,
@NAR_spol varchar(8),
@NAR_ime varchar(20)

AS

INSERT INTO  dbo.Narucitelj ( NAR_Spol, NAR_ime )
VALUES ( @NAR_Spol, @NAR_ime )

SET @NAR_ID_Narucitelja = @@IDENTITY

2. DBML (Database Markup Language) - a LINQ to SQL Classes
Pool table and stored procedure.

3. Calling insert store procedure with output parameter


       DataClassesNaruciteljDataContext DCNaruciteljContext = new
DataClassesNaruciteljDataContext();
       Narucitelj narucitelj = new Narucitelj();
       //definition for output parameter in c#
       System.Nullable

<int > nullableID

 = narucitelj.NAR_ID_Narucitelja;
       DCNaruciteljContext.Insert_Narucitelj(ref nullableID, "Zensko", "Fata");

AJAX: captcha - Create It

2009-05-31T06:02:00.000-07:00

What is captcha: secure picture with randomly generated letters in registration process on asp.net page.

In this demonstration we are going to create captcha, secure picture with letters in registration process. Captcha will be created in asp.net, AJAX and C# technology.

The major thing on captcha will be done in C# code behind.

How to create captcha :

1. Create New aspx page in your Project (name it: Captcha.aspx)
3. Before namespace include this directives:

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;

2. On PageLoad() of Captcha.aspx paste this code (change MapPath and name of picture):

//Folder for pictures under your project
string mpath = Server.MapPath("../../Images/");

string imgFunnyCat = mpath + "funny-cat.jpg";

Bitmap objBMP = new System.Drawing.Bitmap(imgFunnyCat);
Graphics objGraphics = System.Drawing.Graphics.FromImage(objBMP);
//objGraphics.Clear(Color.Green);
objGraphics.TextRenderingHint = TextRenderingHint.AntiAlias;

//' Configure font to use for text
Font objFont = new Font("Arial", 11, FontStyle.Bold);
string randomStr = "";
int[] myIntArray = new int[5];
int x;

//That is to create the random # and add it to our string
Random autoRand = new Random();
for (x = 0; x < 5; x++)
{
myIntArray[x] = System.Convert.ToInt32(autoRand.Next(0, 9));
randomStr += (myIntArray[x].ToString());
}

//This is to add the string to session cookie, to be compared later
Session.Add("randomStr", randomStr);

//' Write out the text
objGraphics.DrawString(randomStr, objFont, Brushes.Black, 20, 8);

string slika = mpath + "aa.jpeg";

//' Set the content type and return the image
Response.ContentType = "image/Jpeg";
//objBMP.Save(slika, ImageFormat.Jpeg);
objBMP.Save(Response.OutputStream, ImageFormat.Jpeg);

objFont.Dispose();
objGraphics.Dispose();
objBMP.Dispose();

4. On other page; Register page (in Design mode), inside of ajax update panel, include Image control and Button control.
Image control should have ImageUrl property to show on Captcha.aspx page

asp:Image ID="Image1" runat="server" ImageUrl="~/UI/Controls/Captcha.aspx" /

and Button property Click shoul have Button1_Click value

asp:Button ID="Button2" runat="server" Text="Button" onclick="Button1_Click" /

5. In code behind of Register page, in button click event you should put code with ImageUrl to show on Captcha.asp page and with generated id. (because, ajax update will happened only if something is changed. And this URL will be generated randomly.

protected void Button1_Click(object sender, EventArgs e)
{
Image1.ImageUrl = "~/UI/Controls/Captcha.aspx?id=" + Guid.NewGuid() + "";
}

collection was modified; enumeration operation my not execute ajax accordion

2009-05-22T05:09:00.000-07:00

PROBLEM:

Visual Studio 2008 Design Mode Errior: Error Rendering Control - Accordion
" collection was modified; enumeration operation my not execute ajax accordion "

SOLUTION:

Change the control size by streching borders.

How do I configure SQL Server 2005 to accept SQL Authentication?

2009-05-13T03:14:00.000-07:00

In this text :

1. How do I configure SQL Server 2005 to accept SQL Authentication?
2. PROBLEM: Create failed for Login
3. PROBLEM: Connection Error
4. How to enable Named Pipes and TCP/IP for Microsoft SQL Server 2005

Configure SQL Server 2005 to accept SQL Authentication

There are 2 methods of authentication by which GFI ReportCenter can authenticate to SQL Server 2005. These are:

- Windows authentication
- SQL Server authentication (or mixed authentication).

In order to use SQL Server authentication you must first configure your server using the steps below.

1. Right-click on the server node and select 'Properties'.

2. Select 'Security' from the left menu under 'Select a page'.

3. Under 'Server Authentication', select the 'SQL Server and Windows Authentication mode option'.

4. Click 'OK' to close the dialog.

5. Right click on the server node and choose 'Restart' for the changes to take affect.

Enable SQL Server login

1. In the server node expand 'Security' and 'Logins'.

2. Right click on the login name and select 'Properties'.

3. Enter a password and confirm the password for the login.

4. Select 'Status' from the left menu under 'Select a page'.

5. Set the 'Login' option to 'Enabled'.

6. Click 'OK' to close the dialog.

PROBLEM : Create failed for Login

When I try to create a new login for some apps for VS with all the default

setttings (all I do is to type in the username and password) and I get this

error:

TITLE: Microsoft SQL Server Management Studio

------------------------------

Create failed for Login 'irenic'. (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.4035.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Create+Login&LinkId=20476

------------------------------

ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

------------------------------

The MUST_CHANGE option is not supported by this version of Microsoft Windows. (Microsoft SQL Server, Error: 15195)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=09.00.1399&EvtSrc=MSSQLServer&EvtID=15195&LinkId=20476

SOLUTION: Create Failed For Login

Uncheck the 'Use must change password on next login'.

PROBLEM 2:Connection Error

Connection Error: (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe

When I try to connect from Virtual Machine to my SQL 2005 Database I get this error:

TITLE: Connect to Server
------------------------------

Cannot connect to IVANA2.

------------------------------
ADDITIONAL INFORMATION:

A connection was successfully established with the server, but then an error occurred during the pre-login handshake. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 0 - No process is on the other end of the pipe.) (Microsoft SQL Server, Error: 233)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=233&LinkId=20476

SOLUTION: Connection Error

Enable the Protocols "Named Pipes" and it will work.

3. How to enable Named Pipes and TCP/IP for Microsoft SQL Server 2005

1. Click Start > Programs > Microsoft SQL Server 2005 > Configuration Tools > SQL Server Configuration Manager.

2. Under SQL Server 2005 Network Configuration > Protocols for MSSQLSERVER:
1. Double-click the protocol name TCP/IP and set the property ENABLED to Yes.
2. Double-click the protocol name Named Pipes and set the property ENABLED to Yes.
3. To restart MS SQL 2005 service, run the following commands in the command prompt:

net stop mssqlserver
net start mssqlserver

Installing the ASP.NET AJAX Control Toolkit (Visual Studio 2008)

2009-05-08T03:03:00.000-07:00

" AjaxControlToolkit.tlb could not be loaded " so, do it on right way :)

The AjaxControlToolkit is not a COM library, it is a regular .NET Assembly. From the toolbox, click "Add items", then on the ".NET Framework Components" tab click browse in the lower right. Select the control toolkit and you should be good to go.

1. Download and Install Microsoft Visual Studio 2008 Service Pack 1
This download installs Visual Studio 2008 Service Pack 1 (SP1) and the .NET Framework 3.5 SP1.

2. Download and Extract AjaxControlToolkit-Framework3.5SP1.zip

3. Make sure the SampleWebSite folder (folder in extracted file) is in a reasonably permanent location on your hard drive.

4. Open Visual Studio 2008 (sp1): You need to create a new Toolbox tab for the controls. Right-click the Toolbox and choose Add Tab. Then, enter a name (like AJAX Toolkit) and hit Enter.

5. You need to add the controls to the new tab. Right-click the blank tab you’ve
created and select Choose Items.

6. In .NET Framework Components click Browse. Find the AjaxControlToolkit.dll
(which is in the SampleWebSite\Bin folder) and click OK.

7. You'll get "Accordion" and "Accordion Pane" checked. Click ok.

The End :)

How to Get and View Process Identifier (Process ID or PID) on Windows

2009-04-26T14:46:00.000-07:00

Process identifier, or more commonly know as PID or process ID, is a unique number tagged with each processes running on a system, and used by some operating system kernels, such as UNIX, Linux, Mac OS X and Windows) to identify a process.

n Unix-like and Linux operating system, ps command can be used to search for the PID for a particular running process, by grepping the output. In Windows operating system such as Windows XP, Windows Vista, Windows Server 2003, Windows Server 2008 and Windows 7, there is no such utility or command available though.

In order to get to know, or view, retrieve and identify the process ID or PID of the processes running in Windows operating system, users or administrators can make use of Task Manager. However, Task Manager does not display PID information by default. To display the PID value in Task Manager, go to Processes tab, click on View menu, then click on Select Columns…. In the “Select Columns” or “Select Process Page Columns” dialog, tick and check the checkbox for PID (Process Identifier), and click OK.

To run Task Manager, use Taskmgr command or right click on Taskbar, and select “Task Manager”.

Mozila Firefox Keyboard Shortcuts

2009-03-24T06:35:00.000-07:00

Taken from Here
Common Shortcuts for IE and Mozila: Here

Command	Shortcut
Navigation
Back	AltOpt+Left Arrow BackspaceAltOpt+Left Arrow CtrlCmd+[CtrlCmd+[ CtrlCmd+Left Arrow Delete
Forward	AltOpt+Right Arrow Shift+BackspaceAltOpt+Right Arrow CtrlCmd+]
Home	AltOpt+Home
Open File	CtrlCmd+O
Reload	F5 Ctrl Cmd+R
Reload (override cache)	CtrlCmd+F5 CtrlCmd+Shift+R
Stop	CtrlCmd+. Esc
Current Page
Go to Bottom of Page	End
Go to Top of Page	Home
Move to Next Frame	F6
Move to Previous Frame	Shift+F6
Page Info	CtrlCmd+I
Page Source	CtrlCmd+U
Print	CtrlCmd+P
Save Page As	CtrlCmd+S
Zoom In	CtrlCmd++
Zoom Out	CtrlCmd+-
Zoom Reset	CtrlCmd+0
Editing
Copy	CtrlCmd+C
Cut	CtrlCmd+X
Delete	Delete
Paste	CtrlCmd+V
Redo	CtrlCmd+YCtrlCmd+Shift+Z
Select All	CtrlCmd+A
Undo	CtrlCmd+Z
Search
Find	CtrlCmd+F
Find Again	F3 CtrlCmd+G
Find As You Type Link	'
Find As You Type Text	/
Find Previous	Shift+F3
Web Search	CtrlCmd+K CtrlCmd+E Ctrl Cmd+J
Windows & Tabs
Close Tab	CtrlCmd+W Ctrl+F4
Close Window	CtrlCmd+Shift+W AltOpt+F4
Move Tab Left (when tab is focused)	CtrlCmd+Left Arrow CtrlCmd+Up Arrow
Move Tab Right (when tab is focused)	CtrlCmd+Right Arrow CtrlCmd+Down Arrow
Move Tab to Beginning (when tab is focused)	Ctrl Cmd+Home
Move Tab to End (when tab is focused)	CtrlCmd+End
New Tab	CtrlCmd+T
New Window	CtrlCmd+N
Next Tab	Ctrl+Tab CtrlCmd+AltOpt+Right Arrow Cmd+} Ctrl+Page Down
Open Address in New Tab (from Location Bar or Search Bar)	AltOpt+EnterReturn
Previous Tab	Ctrl+Shift+Tab CtrlCmd+AltOpt+Left Arrow Cmd+{ Ctrl+Page Up
Undo Close Tab	CtrlCmd+Shift+T
Select Tab (1 to 8)	CtrlCmdAltOpt+(1 to 8)
Select Last Tab	CtrlCmdAltOpt+9
Tools
Bookmark All Tabs	CtrlCmd+Shift+D
Bookmark This Page	CtrlCmd+D
Bookmarks	CtrlCmd+B CtrlCmd+I
Caret Browsing	F7
Downloads	CtrlCmd+JCtrlCmd+Y
History	CtrlCmd+H CtrlCmd+Shift+H
Clear Private Data	CtrlCmd+Shift+Del
Error Console	CtrlCmd+Shift+J
Miscellaneous
Complete .com Address	CtrlCmd+EnterReturn
Complete .net Address	Shift+EnterReturn
Complete .org Address	CtrlCmd+Shift+EnterReturn
Delete Selected Autocomplete Entry	DelShift+Del
Full Screen	F11
Help	F1Cmd+?
Select Location Bar	Alt+D F6 CtrlCmd+L
Select or Manage Search Engines (when Search Bar is focused)	AltOpt+Up Arrow AltOpt+Down Arrow F4

Dll : How to create and use dll in Visual Basic 6

2009-03-23T06:53:00.000-07:00

This is short tutorial of crating and using dll.

DLL CREATING:

1. Start Miscrosoft Visual Basic 6
2. File/ New Project
3. Choose: ActiveX DLL
4. Write some functions or what you need. If you wish to use it, it sholud not be private.
5. Change project and class name and save projetct! (File/ Save As..)
6. Make dll: File/Make dllName.dll

REGISTER DLL:

1. Start/Run
2. regsvr32 and (drag/drop) dll ... to unregister regsvr32 /u and (drag/droo)dll
3. Enter

USE DLL IN SOME OTHER PROJECT:
To use dll in some project you ned to make reference to that dll.

1. Open the project that will use dll.
2 Project/References
3 Browse to the .dll you wish to use.

REGISTER DLL IN THE PROJECT.

To use classes from dll you need to create object.

1. Dim nameOfObject As dllName.ClassName
2. Set nameOfObject= New dllName.ClassName
3. nameOfObject.ClassFunctions

javascript intellisense in visual studio 2005

2009-03-11T04:24:00.000-07:00

You can use the Visual Studio 2005 IDE to edit your Classic ASP files and still utilize syntax highlighting and intellisense. All you have to do is associate the “.asp“ file extension with the Web Form Editor. When doing this you are telling the IDE to treat “.asp“ files the same as “.aspx“ files, in turn sort of “tricking“ the IDE in to giving you the syntax highlighting and intellisense that you want.

The steps in setting up the IDE are as follows:

1. Open Visual Studio
2. Goto the "Tools" menu and click "Options..."
3. Check the "Show all options" checkbox in the bottom left of the dialog box.
4. In the right pane expand "Text Editor" and select "File Extension"
5. Enter "ASP" extension in the "Extension" textbox
6. Select "Web Form Editor" in the Editor dropdown box
7. Click the "Add" button and click "Ok" on the dialog box.

And now enjoy all the syntax highlighting and intellisense features for JavaScript, HTML and Visual Basic while editing your Classic ASP files

Option Explicit

2009-03-09T00:09:00.000-07:00

<%Option Explicit%>

Forces explicit declaration of all variables in a file.

If used, the Option Explicit statement must appear in a file before any other source code statements.

When Option Explicit appears in a file, you must explicitly declare all variables using the Dim or ReDim statements. If you attempt to use an undeclared variable name, an error occurs at compile time.

Use Option Explicit to avoid incorrectly typing the name of an existing variable or to avoid confusion in code where the scope of the variable is not clear. If you do not use the Option Explicit statement, all undeclared variables are of Object type.

Dim thisVar As Integer ' ok
thisVar = 10 ' ok

' The following assignment produces a COMPILER ERROR because
' the variable is not declared and Option Explicit is On.
thisInt = 10 ' causes ERROR

An Overview of Classic ASP's Request Object

2009-03-06T00:04:00.000-08:00

The Request Object receives the values that the client's browser passed to the server during an HTTP request.

When you surf to an address that begins with HTTP, the server you're visiting treats that as an "HTTP request"; you are in fact "requesting" that a particular web page is displayed to you. The same applies to any http hyperlinks that you click. A lot more information is being passed back and forth, between your PC and the server of the site you're visiting, than you may be aware of. This chunk of data is called a "request object". Along with the URL you've requested, information about your browser, IP address, the last URL you visited and more is being sent along with your request to view a particular web page. On the flip side, in addition to the web page you requested, the server also sends back server-related information in the same request object.

All this data gets passed in the HTTP request (a.k.a Request Object). Whether it was posted via an online form you filled in ..or.. embedded in the URL as name-value pairs, it all ends up in the Request object. How does that happen, you wonder? That's a helpful feature of Microsoft IIS (internet information services), whereas systems/languages such as Unix/Perl must parse/extract that information manually.

To make life a little simpler, the Request Object has several "collections". A collection is just a fancy word for grouping, segregating or classifying all of the information that's being exchanged. For example, input-capable fields on a form that is sent via "method=post" end up in collection "Form", while name-value pairs sent in the URL (or from a form sent via "method=get") end up in collection "QueryString", etc.

ClientCertificate: The values of fields stored in the client certificate that is sent in the HTTP request.
Cookies: The values of cookies sent in the HTTP request.
Form: The values of form elements in the HTTP request body.
QueryString: The values of variables in the HTTP query string.
ServerVariables: The values of predetermined server/environment variables.

The syntax is:
Request[.collection|property|method](variable)

All request object variables can be accessed directly by calling Request(variable) without the collection name. In this case, the Web server searches the collections in the following order:

QueryString
Form
Cookies
ClientCertificate
ServerVariables

If a variable with the same name exists in more than one collection, the Request object returns the first instance encountered. It is strongly recommended that, when referring to members of the ServerVariables collection, the full name be used. For example, rather than Request("AUTH_USER") use Request.ServerVariables("AUTH_USER").

From Here

WINSXS : What is the WINSXS directory in Windows 2008 and Windows Vista and why is it so large?

2009-03-04T15:04:00.000-08:00

A commonly asked question among people looking at a Windows Vista or Windows Server 2008 installation is “why is the WinSxS folder so big?!” To answer that question I need to first describe componentization, and how components are managed in Windows Vista.

One of the largest changes between previous versions of Windows and Windows Vista was a move from an INF described OS to componentization. A component in Windows is one or more binaries, a catalog file, and an XML file that describes everything about how the files should be installed. From associated registry keys and services to what kind security permissions the files should have. Components are grouped into logical units, and these units are used to build the different Windows editions.

All of the components in the operating system are found in the WinSxS folder – in fact we call this location the component store. Each component has a unique name that includes the version, language, and processor architecture that it was built for. The WinSxS folder is the only location that the component is found on the system, all other instances of the files that you see on the system are “projected” by hard linking from the component store. Let me repeat that last point – there is only one instance (or full data copy) of each version of each file in the OS, and that instance is located in the WinSxS folder. So looked at from that perspective, the WinSxS folder is really the entirety of the whole OS, referred to as a "flat" in down-level operating systems. This also accounts for why you will no longer be prompted for media when running operations such as System File Checker (SFC), or when installing additional features and roles.

That explains why the folder starts off big, but not why it gets larger over time – the answer to that question is servicing. In previous versions of Windows the atomic unit of servicing was the file, in Windows Vista it’s the component. When we update a particular binary we release a new version of the whole component, and that new version is stored alongside the original one in the component store. The higher version of the component is projected onto the system, but the older version in the store isn’t touched. The reason for that is the third part of why the component store gets so large.

Not every component in the component store is applicable, meaning that not every component should be projected onto the system. For example, on systems where IIS is available but has not been installed, the IIS components are present in the store, but not projected into any location on the system where they might be used. If you’re familiar with how multi-branch servicing works in previous versions of Windows then it’ll make sense to you that we have a different version of the component for each distribution branch and service pack level, and that all these different versions are also stored in the WinSxS folder, even if they’re not immediately applicable. So a single Post SP1 GDR package that contains an update to one component will end up installing four versions of that component in the WinSxS folder – double that on a 64 bit operating system for some components.

Now that you know why the store can grow to be so large, your next question is probably to ask why we don’t remove the older versions of the components. The short answer to that is reliability. The component store, along with other information on the system, allows us to determine at any given time what the best version of a component to project is. That means that if you uninstall a security update we can install the next highest version on the system – we no longer have an “out of order uninstall” problem. It also means that if you decide to install an optional feature, we don’t just choose the RTM version of the component, we’ll look to see what the highest available version on the system is. As each component on the system changes state that may in turn trigger changes in other components, and because the relationships between all the components are described on the system we can respond to those requirements in ways that we couldn’t in previous OS versions.

Reduce the size of WinSxS:

The only way to safely reduce the size of the WinSxS folder is to reduce the set of possible actions that the system can take – the easiest way to do that is to remove the packages that installed the components in the first place. This can be done by uninstalling superseded versions of packages that are on your system. Service Pack 1 contains a binary called VSP1CLN.EXE, a tool that will make the Service Pack package permanent (not removable) on your system, and remove the RTM versions of all superseded components. This can only be done because by making the Service Pack permanent we can guarantee that we won’t ever need the RTM versions.

So yes, the WinSXS folder is very large, and it will continue to grow as the OS ages. I hope that this clears up some of the questions about why that is, and what you can do about it. Note that the Windows servicing structure and the layout of the store is subject to change.

Joseph Conway
Senior Support Escalation Engineer
Microsoft Enterprise Platforms Support

From Here

winsxs mistery! VISTA (hrvatski)

2009-03-04T14:51:00.000-08:00

uzeto: link

Uvod (Problem)
Imao sam jednu particiju rezervisanu za testiranja operativnih sistema, odlaganje slika virtuelnih mašina i sl. Tih 15GB odlučim popuniti Vista OS-om i to AMD64 verzijom. Nije me brinulo koliko
Vista zauzima RAM-a, sa 4GB to nije bio problem. Nisam ništa “tweak”-ao, želio sam uživati u svim čarima koje je vista nudila (Aero fazoni i sl.).

Jedna stvar me ipak zabrinula - zazuzeće prostora na disku. Od 15GB presotalo mi je samo 2GB. Provjerim Recycle Bin, isključim korištenje korpe za C:\, te provjerim Pagefile - Vista ga stavila na drugu particiju, isključim System Restore… ista stvar. Skinem jedan program za pregled direktorija/prikaz veličine i zapazim zabrinjavajuću stvar. Unutar “windows” direktorija postoji jedan drugi pod nazivom “winsxs” koji (u mom slučaju) zauzimao 8.5GB.

Pretražujući po internetu primjetio sam da se svi Vista korisnici žale na istu stvar a to je da im je ovaj folder prevelik, i to varira od ~5GB do ~8GB. Treba napomenuti da se ovaj direktorij “napuše” do 8GB nakon čiste instalacije i skidanja najnovijih update-a.

Čemu služi ovaj direktorij?
Uh, hu, huuu! WinSxS je skračenica od “Windows Side-by-Side“. U začecima Windows je imao problema sa dijeljenim “.dll” datotekama, gdje se dešavalo da jedan program pri deinstalaciji obriše, za njega nepotrebne, “.dll”-ove a koji su neophodni za ispravan rad drugog programa na računaru. Izdavanjem novijih verzija Windows-a stvar je sve bolje riješavana i stavljena pod kontrolu. “winsxs” direktorij kod WinXP-a iznosi svega ~50MB.

Vista nema i386 folder za keširanje datoteka, i korištenje “.ini” datoteka je prevaziđeno i umjesto toga se koriste XML katalozi sa detaljnim opisom čemu i za šta služi datoteka te za koju je platformu namjenjena.

Sa Vista OS-om, napravljen je korak dalje, a to je da se zasebno čuvaju različite verzije istih “.dll”-ova kako bi se povečala kompatibilnost i stabilnost. Nadalje povečana je sigurnost u odnos na WinXP i Server 2003. Sada jedini vlasnik/grupa nad ovim direktorijem je SID pod nazivom “Trusted Installer”, u prevodu ovo znači da (u normalnim okolnostima) ni administrator ne može brisati/mijenjati datoteke, direktorije i sl.

Ako pogledate unutar ovog foldera, primjetit ćete mnogo foldera istovjetnog naziva sa razlikom u zadnjih osam karaktera koji su najčešće nasumični nizovi brojeva i slova.

Šta možemo uraditi?

a) Pazit koliko instaliramo (koja bolest)
Očajnički sam tražio odobrenje i opravdanje da počnem brisati sumnjive datoteke i direktorije iz winsxs-a, ali nisa mogao nać. Za sada sve što ćete nači na internetu po forumima je da se držite podalje od ovog direktorija i da ga ne dirate jer bi pojedine aplikacije a i sam Windows mogli kolapsirati. Kod Vista SP1, brisanje pojedinih datoteka iz ovog direktorija ili njegovo izmještanje izaziva BSoD. Jer mnoge sistemske datoteke unutar %windows%\system32 direktorija su samo “hard link*”-ovane na one koji se nalaze unutar %windows%\winsxs direktorija, pa njegovo izmještanje ili brisanje pojedinih datoteka automatski prekida i veze ka njemu.

Najbolje bi bilo da vaš Vista OS pogurate “dohranite” diskom večeg kapaciteta i zaboravite na ovaj direktorij. Dalje potrebno je da korigujete svoje navike, ako ste od onih ljudi koji vole eksperimentisati programima/aplikacijama - winsxs će zasigurno da se brzo puni. Dakle što manje instalacija i deinstalacija!

*hard link - jedna od mogućnosti datotetičnih sistema koja omogučava kreiranje više (naziva) datoteka koji ustvari upućuju na jednu datoteku.

b) VSP1CLN.EXE,

Quick call Windows Login Screen

2009-02-25T15:32:00.000-08:00

windows logo key +L

How to register dll, How to re-register dll, How to register multiple dlls, How to Unregister dll

2009-02-19T05:19:00.000-08:00

How to register dll and How to re-register dll?

1. Click Start and Run and wrote: regsvr32 path\filename.dll
(you can wrote or drag and drop file to set path and filename
and you can register more then one dll with one regsvr32 commads. Just drag couple of dll files )

2. press Enter.

Example:
regsvr32 C:\config\servercomponents\Blabla.dll

- regsvr32 is a command that tells your computer to register the DLL file
- path is the actually location or directory of where the file is located.
- filename is obviously the name of the DLL file you will be registering

Once the DLL has been registered, you should receive a confirmation in the form of a pop up box. This message will list your newly registered DLL file and confirm that is was successfully registered into the registry.

How to Unregister dll ?

Start and Run and wrote: regsvr32 /u path\filename.dll

Example:
regsvr32 /u C:\config\servercomponents\Truckscout.dll

Vista: "You need permission to perform this action”

2009-02-11T09:38:00.000-08:00

The best part is that you do not get this error on any kind of consistent basis, it can pop up when you are trying to delete a folder, trying to copy some files, trying to install a program, etc, etc. It all comes down to not having the right security permissions.

Note that UAC (User Account Control) does not usually affect this problem, so don’t go out and automatically disable UAC. If you disable UAC, you can’t do things like share printers, etc, so it’s best to live with it.

There are some things you can do, however, to help out with the “You do not have permission to perform this action” problem though. If it’s a particular file or folder you are trying to delete, you can simply give yourself full control permissions over the file.

But before we go into that, try one other method that might be a bit faster. Go to Start, Programs, Accessories, and right-click on the command prompt and choose Run as Administrator.

Now at the command prompt type the following command:

net user administrator /active:yes

Press Enter and restart your computer. Now try to perform the task again that gave you the “You do not have permission” error. If that does not work, then follow the steps below to change the file permissions.

To change the security permissions for a file, right-click on the file and go to Properties. Then click on the Security tab.

Now click on the Advanced button at the bottom and click on the Owner tab.

Click on the Edit button, click Other users and groups and type in your user account name and click Check Names.

Click OK and on the Owner tab make sure to check the “Replace owner on subcontainers and objects” box. Now select your user account from the list on the Security tab and click Edit. Click Allow next to Full Control and click OK.

Hopefully, this fixes one very annoying problem with Windows Vista. I did notice that upgrading to SP1 helped to reduce the occurrence of this error, so if you do not have SP1 installed yet, make sure to go to Windows Update. Enjoy!

ByVal vs ByRef (Difference between ByVal and ByRef)

2009-01-29T06:58:00.000-08:00

The difference between ByVal and ByRef is very simple once we recall the subject on pointers. These keywords are simply abbreviations of the full definition of the differences between the two.

ByVal = By Value and ByRef = By Reference

Now we can recall what I said in the previous chapter about C/C++ and pointers. Pointers act as a Reference to a memory address location. In VB however, this means that the reference is occurring in your statement directly at the location of the actual data, and where it is stored.

Selecting a ByVal would thereby mean you are only working on a copy or replica of the data, and not the actual data segment it self.

This has specific implications for how your statements can handle and alter the data in your variable. The ByRef use, would imply that a change performed by the statement of the value you pass, has an affect on the actual data, while the ByVal use would only alter the copy the statement has to work on.

Simply described, if passed ByRef, a procedure can permanently alter the data stored in the variable. Since it also is faster to send a memory address location, rather than passing a copy of a data argument, it is the default value used by Visual Basic.

How to Ghost Windows Vista hard disk hdd in the notebook computer

2009-01-28T14:13:00.000-08:00

Notebook normally comes with small size hard disk. Soon, you will find the hard disk (hdd) is full. Reinstall Windows Vista, Microsoft Office 2007, all the other software will take a long time. Even have all the original CDs is not enough -- all the software these days require to have code, activation. Replacing a big size hard disk is a bigger headache.

Ghost from Norton was a great utility to use to make disk image. It works from DOS, Windows 98, Windows 2000, Windows XP, and Windows XP with SP2. It also works for Vista, right? Wrong!

What is wrong with Vista? Microsoft changed how the boot is handled in the Vista. All the older version Ghost does not know how to handle it. So you make perfect image copy of your notebook hard drive to this new bigger hard disk, but it will not boot. When you try to boot, it says "unable to access \windows\winload.exe". Ghost copied bootloader, but the boot loader still expect the old disk. With each disk has different device name and ID, it does not match up, so it will not boot.

Here is the method to rescure from this situation:

1) Install the newly cloned Vista hdd in the notebook, do not boot yet;
2) Power on your notebook computer with Vista installation CD in the CD/DVD drive;
3) Make sure your computer is boot from the CD/DVD, not hard disk -- very important;
4) Select the proper language of your installation, then Next;
5) Select "Repair" on next screen;
6) Let installation CD finish scanning the system for Windows installations;
7) It may prompt you the current installation on HDD is corrupted, would you like to repair. Select No;
8) Next screen it will have a selection of commands, select "Command Prompt";
9) Vista has a command called "BCDEDIT", type that and enter;
10) Write down what's on screen on a piece of paper. The information is important;
11) Noticed under "bootmgr", "default", and "osdevice", all says device unknown;
12) Type exactly next three lines, each followed by the "Enter" key:

bcdedit /set {bootmgr} device boot
bcdedit /set {default} device boot
bcdedit /set {default} osdevice boot

13) Close the Command Prompt windows, take out the installation DVD, and click on "Restart"
14) Once the computer boot, call Microsoft to reactive your Vista on this new hard disk!

Visual Basic 6 instalation problems ( acmboot.exe )

2009-01-19T05:32:00.000-08:00

For some reason, when I try to install Visual Studio 6.0, I encounter an error that states that "acmboot.exe is damaged". Is there a way to fix this problem, or do I need to get my install disc for this program replaced?

********* SOLUTION **********
Error Launching D:\....\acmboot.exe.
1. make a copy of your installation cd in your hard drive
2. make a copy of the setup/VS98ENT.STF and name it acmsetup.STF
3. copy entire content of setup/ to previous folder (the one that has acmboot.exe file)
4. modify acmsetup.stf with acost.exe as you require and save it.
5. run acmsetup.exe instead of setup (the one that's on the same path as acmboot.exe)
6. voala, that's it, your visual studio 6.0 will be installed.

How to check IP address?

2009-01-12T05:04:00.000-08:00

Start - Run - cmd - ipconfig + Enter

Backing up your IIS 6.0 Metabase

2008-12-15T00:59:00.000-08:00

Preface:

In previous versions of Internet Information Services (IIS) configurations were stored in the registry. Part of IIS 6.0's rebuilding was changing where the configuration is stored, which is now a file named MetaBase.xml in your \WINDOWS\system32\inetsrv directory. Sure, you can copy that file (and possibly MBSchema.bin.00000000h) to a separate directory, but a smarter way to do this is to use IIS 6.0's built-in back-up mechanism. There are 2 ways to do this, but I'll only be showing you the graphical one at the moment.

Method:

(Backing up Internet Information Service 6.0)
Load IIS from the Administrative tools in the Control Panel by clicking Start -> Administrative Tools -> IIS Manager (or loading the Control Panel, entering the Administrative Tools folder, and double clicking IIS Manager).

Right click your computer name, put your mouse over "All tasks" and click "Backup/Restore Configuration"

Click Create Backup

Now you can make up any name you want, not including dots (.) You can also password protect the back up if you choose. IMPORTANT: If you wish to restore this IIS backup to the other computers then you should include and remember password!

That's it, you're done! To restore the backup you can now select the backup you just made and press the Restore button

Your backup is stored in C:\WINDOWS\system32\inetsrv\MetaBack under the name you gave it. Actually, it will be 2 files. In the example I gave above 2 files were created:

visualwin backup.MD0
visualwin backup.SC0

I recommend the copying of these files to another folder, just in case.

How do you find a DNS server address MAC and Windows?

2008-11-12T08:23:00.000-08:00

If you are using a PC, click the start button. Select the run command. Type CMD into the box and press enter. When the black box pops up type the following line in

ipconfig /all

Look through the data to see what your DNS address is.

If you are using a mac. Go to the System Preferences. Click on the Network Icon Double Click on the Ethernet icon if you have an ethernet cable plugged in (Looks like a wide phone jack) Double Click on the Airport card if you are using wireless internet. The DNS servers will be listed under the TCP/IP Tab.

HOW TO LUNCH explorer.exe

2008-10-22T06:52:00.000-07:00

If you killed your explorer.exe by mistake...here is how to run it again:

From Task Manager, execute EXPLORER.EXE;
Hit
Ctrl-Alt-Del and load Task manager.
File --> New Task (run)-->EXPLORER.EXE

Deleting Files Without Recycle Bin

2008-08-25T13:51:00.000-07:00

Select the files or folders you wish to delete then hold the Shift key and press the Delete button. This will delete files bypassing the recycle bin.

For the people who dont know the Shift + Del function, it is a fast way of deleting a file permanently from your pc without using the recycle bin. The only thing different is that its very hard to recover a shift deleted file.

Lesson 07: Using Stored Procedures

2008-08-13T06:14:00.001-07:00

This lesson shows how to use stored procedures in your data access code. Here are the objectives of this lesson:

Learn how to modify the SqlCommand object to use a stored procedure.
Understand how to use parameters with stored procedures.

Introduction

A stored procedures is a pre-defined, reusable routine that is stored in a database. SQL Server compiles stored procedures, which makes them more efficient to use. Therefore, rather than dynamically building queries in your code, you can take advantage of the reuse and performance benefits of stored procedures. The following sections will show you how to modify the SqlCommand object to use stored procedures. Additionally, you'll see another reason why parameter support is an important part of the ADO.NET libraries.

Executing a Stored Procedure

In addition to commands built with strings, the SqlCommand type can be used to execute stored procedures. There are two tasks require to make this happen: let the SqlCommand object know which stored procedure to execute and tell the SqlCommand object that it is executing a stored procedure. These two steps are shown below:

 // 1.  create a command object identifying
 //     the stored procedure
 SqlCommand cmd  = new SqlCommand(
  "Ten Most Expensive Products", conn);

 // 2. set the command object so it knows
 //    to execute a stored procedure
 cmd.CommandType = CommandType.StoredProcedure;

While declaring the SqlCommand object above, the first parameter is set to "Ten Most Expensive Products". This is the name of a stored procedure in the Northwind database. The second parameter is the connection object, which is the same as the SqlCommand constructor used for executing query strings.

The second command tells the SqlCommand object what type of command it will execute by setting its CommandType property to the StoredProcedure value of the CommandType enum. The default interpretation of the first parameter to the SqlCommand constructor is to treat it as a query string. By setting the CommandType to StoredProcedure, the first parameter to the SqlCommand constructor will be interpreted as the name of a stored procedure (instead of interpreting it as a command string). The rest of the code can use the SqlCommand object the same as it is used in previous lessons.

Sending Parameters to Stored Procedures

Using parameters for stored procedures is the same as using parameters for query string commands. The following code shows this:

 // 1.  create a command object identifying
 //     the stored procedure
 SqlCommand cmd  = new SqlCommand(
  "CustOrderHist", conn);

 // 2. set the command object so it knows
 //    to execute a stored procedure
 cmd.CommandType = CommandType.StoredProcedure;

 // 3. add parameter to command, which
 //    will be passed to the stored procedure
 cmd.Parameters.Add(
  new SqlParameter("@CustomerID", custId));

The SqlCommand constructor above specifies the name of a stored procedure, CustOrderHist, as its first parameter. This particular stored procedure takes a single parameter, named @CustomerID. Therefore, we must populate this parameter using a SqlParameter object. The name of the parameter passed as the first parameter to the SqlParameter constructor must be spelled exactly the same as the stored procedure parameter. Then execute the command the same as you would with any other SqlCommand object.

A Full Example

The code in Listing 1 contains a full working example of how to use stored procedures. There are separate methods for a stored procedure without parameters and a stored procedure with parameters.

Listing 1: Executing Stored Procedures

using System;
using System.Data;
using System.Data.SqlClient;

class StoredProcDemo
{
 static void Main()
 {
  StoredProcDemo spd = new StoredProcDemo();

  // run a simple stored procedure
  spd.RunStoredProc();

  // run a stored procedure that takes a parameter
  spd.RunStoredProcParams();
 }

 // run a simple stored procedure
 public void RunStoredProc()
 {
  SqlConnection conn = null;
  SqlDataReader rdr  = null;

  Console.WriteLine("\nTop 10 Most Expensive Products:\n");

  try
  {
   // create and open a connection object
   conn = new
    SqlConnection("Server=(local);DataBase=Northwind;Integrated Security=SSPI");
   conn.Open();

   // 1.  create a command object identifying
   //     the stored procedure
   SqlCommand cmd  = new SqlCommand(
    "Ten Most Expensive Products", conn);

   // 2. set the command object so it knows
   //    to execute a stored procedure
   cmd.CommandType = CommandType.StoredProcedure;

   // execute the command
   rdr = cmd.ExecuteReader();

   // iterate through results, printing each to console
   while (rdr.Read())
   {
    Console.WriteLine(
     "Product: {0,-25} Price: ${1,6:####.00}",
     rdr["TenMostExpensiveProducts"],
     rdr["UnitPrice"]);
   }
  }
  finally
  {
   if (conn != null)
   {
    conn.Close();
   }
   if (rdr != null)
   {
    rdr.Close();
   }
  }
 }

 // run a stored procedure that takes a parameter
 public void RunStoredProcParams()
 {
  SqlConnection conn = null;
  SqlDataReader rdr  = null;

  // typically obtained from user
  // input, but we take a short cut
  string custId = "FURIB";

  Console.WriteLine("\nCustomer Order History:\n");

  try
  {
   // create and open a connection object
   conn = new
    SqlConnection("Server=(local);DataBase=Northwind;Integrated Security=SSPI");
   conn.Open();

   // 1.  create a command object identifying
   //     the stored procedure
   SqlCommand cmd  = new SqlCommand(
    "CustOrderHist", conn);

   // 2. set the command object so it knows
   //    to execute a stored procedure
   cmd.CommandType = CommandType.StoredProcedure;

   // 3. add parameter to command, which
   //    will be passed to the stored procedure
   cmd.Parameters.Add(
    new SqlParameter("@CustomerID", custId));

   // execute the command
   rdr = cmd.ExecuteReader();

   // iterate through results, printing each to console
   while (rdr.Read())
   {
    Console.WriteLine(
     "Product: {0,-35} Total: {1,2}",
     rdr["ProductName"],
     rdr["Total"]);
   }
  }
  finally
  {
   if (conn != null)
   {
    conn.Close();
   }
   if (rdr != null)
   {
    rdr.Close();
   }
  } 
 }
}

The RunStoredProc method in Listing 1 simply runs a stored procedure and prints the results to the console. In the RunStoredProcParams method, the stored procedure used takes a single parameter. This demonstrates that there is no difference between using parameters with query strings and stored procedures. The rest of the code should be familiar to those who have read previous lessons in this tutorial.

Summary

To execute stored procedures, you specify the name of the stored procedure in the first parameter of a SqlCommand constructor and then set the CommandType of the SqlCommand to StoredProcedure. You can also send parameters to a stored procedure by using SqlParameter objects, the same way it is done with SqlCommand objects that execute query strings. Once the SqlCommand object is constructed, you can use it just like any other SqlCommand object as described in previous lessons.

Lesson 06: Adding Parameters to Commands

2008-08-13T06:11:00.000-07:00

This lesson shows you how to use parameters in your commands. Here are the objectives of this lesson:

Understand what a parameter is.
Be informed about the benefits of using parameters.
Learn how to create a parameter.
Learn how to assign parameters to commands.

Introduction

When working with data, you'll often want to filter results based on some criteria. Typically, this is done by accepting input from a user and using that input to form a SQL query. For example, a sales person may need to see all orders between specific dates. Another query might be to filter customers by city.

As you know, the SQL query assigned to a SqlCommand object is simply a string. So, if you want to filter a query, you could build the string dynamically, but you wouldn't want to. Here is a bad example of filtering a query.

 // don't ever do this!
 SqlCommand cmd = new SqlCommand(
  "select * from Customers where city = '" + inputCity + "'";

Don't ever build a query this way! The input variable, inputCity, is typically retrieved from a TextBox control on either a Windows form or a Web Page. Anything placed into that TextBox control will be put into inputCity and added to your SQL string. This situation invites a hacker to replace that string with something malicious. In the worst case, you could give full control of your computer away.

Instead of dynamically building a string, as shown in the bad example above, use parameters. Anything placed into a parameter will be treated as field data, not part of the SQL statement, which makes your application much more secure.

Using parameterized queries is a three step process:

Construct the SqlCommand command string with parameters.
Declare a SqlParameter object, assigning values as appropriate.
Assign the SqlParameter object to the SqlCommand object's Parameters property.

The following sections take you step-by-step through this process.

preparing a SqlCommand Object for Parameters

The first step in using parameters in SQL queries is to build a command string containing parameter placeholders. These placeholders are filled in with actual parameter values when the SqlCommand executes. Proper syntax of a parameter is to use an '@' symbol prefix on the parameter name as shown below:

 // 1. declare command object with parameter
 SqlCommand cmd = new SqlCommand(
  "select * from Customers where city = @City", conn);

In the SqlCommand constructor above, the first argument contains a parameter declaration, @City. This example used one parameter, but you can have as many parameters as needed to customize the query. Each parameter will match a SqlParameter object that must be assigned to this SqlCommand object.

Declaring a SqlParameter Object

Each parameter in a SQL statement must be defined. This is the purpose of the SqlParameter type. Your code must define a SqlParameter instance for each parameter in a SqlCommand object's SQL command. The following code defines a parameter for the @City parameter from the previous section:

 // 2. define parameters used in command object
 SqlParameter param  = new SqlParameter();
 param.ParameterName = "@City";
 param.Value         = inputCity;

Notice that the ParameterName property of the SqlParameter instance must be spelled exactly as the parameter that is used in the SqlCommand SQL command string. You must also specify a value for the command. When the SqlCommand object executes, the parameter will be replaced with this value.

Associate a SqlParameter Object with a SqlCommand Object

For each parameter defined in the SQL command string argument to a SqlCommand object, you must define a SqlParameter. You must also let the SqlCommand object know about the SqlParameter by assigning the SqlParameter instance to the Parameters property of the SqlCommand object. The following code shows how to do this:

 // 3. add new parameter to command object
 cmd.Parameters.Add(param);

The SqlParameter instance is the argument to the Add method of the Parameters property for the SqlCommand object above. You must add a unique SqlParameter for each parameter defined in the SqlCommand object's SQL command string.

Putting it All Together

You already know how to use SqlCommand and SqlDataReader objects. The following code demonstrates a working program that uses SqlParameter objects. So, everything should be familiar by now, except for the new parts presented in this article:

Listing 1: Adding Parameters to Queries

using System;
using System.Data;
using System.Data.SqlClient;

class ParamDemo
{
 static void Main()
 {
  // conn and reader declared outside try
  // block for visibility in finally block
  SqlConnection conn   = null;
  SqlDataReader reader = null;

  string inputCity = "London";

  try
  {
   // instantiate and open connection
   conn =  new
    SqlConnection("Server=(local);DataBase=Northwind;Integrated Security=SSPI");
   conn.Open();

   // don't ever do this!
//   SqlCommand cmd = new SqlCommand(
//    "select * from Customers where city = '" + inputCity + "'";

   // 1. declare command object with parameter
   SqlCommand cmd = new SqlCommand(
    "select * from Customers where city = @City", conn);

   // 2. define parameters used in command object
   SqlParameter param  = new SqlParameter();
   param.ParameterName = "@City";
   param.Value         = inputCity;

   // 3. add new parameter to command object
   cmd.Parameters.Add(param);

   // get data stream
   reader = cmd.ExecuteReader();

   // write each record
   while(reader.Read())
   {
    Console.WriteLine("{0}, {1}",
     reader["CompanyName"],
     reader["ContactName"]);
   }
  }
  finally
  {
   // close reader
   if (reader != null)
   {
    reader.Close();
   }

   // close connection
   if (conn != null)
   {
    conn.Close();
   }
  }
 }
}

The code in Listing 1 simply retrieves records for each customer that lives in London. This was made more secure through the use of parameters. Besides using parameters, all of the other code contains techniques you've learned in previous lessons.

Summary

You should use parameters to filter queries in a secure manner. The process of using parameter contains three steps: define the parameter in the SqlCommand command string, declare the SqlParameter object with applicable properties, and assign the SqlParameter object to the SqlCommand object. When the SqlCommand executes, parameters will be replaced with values specified by the SqlParameter object.

Lesson 05: Working with Disconnected Data - The DataSet and SqlDataAdapter

2008-08-13T06:08:00.001-07:00

This lesson explains how to work with disconnected data, using the DataSet and SqlDataAdapter objects. Here are the objectives of this lesson:

Understand the need for disconnected data.
Obtain a basic understanding of what a DataSet is for.
Learn to use a SqlDataAdapter to retrieve and update data.

Introduction

In Lesson 3, we discussed a fully connected mode of operation for interacting with a data source by using the SqlCommand object. In Lesson 4, we learned about how to read data quickly an let go of the connection with the SqlDataReader. This Lesson shows how to accomplish something in-between SqlConnection and SqlDataReader interaction by using the DataSet and SqlDataAdapter objects.

A DataSet is an in-memory data store that can hold numerous tables. DataSets only hold data and do not interact with a data source. It is the SqlDataAdapter that manages connections with the data source and gives us disconnected behavior. The SqlDataAdapter opens a connection only when required and closes it as soon as it has performed its task. For example, the SqlDataAdapter performs the following tasks when filling a DataSet with data:

Open connection
Retrieve data into DataSet
Close connection

and performs the following actions when updating data source with DataSet changes:

Open connection
Write changes from DataSet to data source
Close connection

In between the Fill and Update operations, data source connections are closed and you are free to read and write data with the DataSet as you need. These are the mechanics of working with disconnected data. Because the applications holds on to connections only when necessary, the application becomes more scalable.

A couple scenarios illustrate why you would want to work with disconnected data: people working without network connectivity and making Web sites more scalable. Consider sales people who need customer data as they travel. At the beginning of the day, they'll need to sync up with the main data base to have the latest information available. During the day, they'll make modifications to existing customer data, add new customers, and input new orders. This is okay because they have a given region or customer base where other people won't be changing the same records. At the end of the day, the sales person will connect to the network and update changes for overnight processing.

Another scenario is making a Web site more scalable. With a SqlDataReader, you have to go back to the data base for records every time you show a page. This requires a new connection for each page load, which will hurt scalability as the number of users increase. One way to relieve this is to use a DataSet that is updated one time and stored in cache. Every request for the page checks the cache and loads the data if it isn't there or just pulls the data out of cache and displays it. This avoids a trip to the data base, making your application more efficient.

Exceptions to the scenario above include situations where you need to update data. You then have to make a decision, based on the nature of how the data will be used as to your strategy. Use disconnected data when your information is primarily read only, but consider other alternatives (such as using SqlCommand object for immediate update) when your requirements call for something more dynamic. Also, if the amount of data is so large that holding it in memory is impractical, you will need to use SqlDataReader for read-only data. Really, one could come up with all kinds of exceptions, but the true guiding force should be the requirements of your application which will influence what your design should be.

Creating a DataSet Object

There isn't anything special about instantiating a DataSet. You just create a new instance, just like any other object:

DataSet dsCustomers = new DataSet();

The DataSet constructor doesn't require parameters. However there is one overload that accepts a string for the name of the DataSet, which is used if you were to serialize the data to XML. Since that isn't a requirement for this example, I left it out. Right now, the DataSet is empty and you need a SqlDataAdapter to load it.

Creating A SqlDataAdapter

The SqlDataAdapter holds the SQL commands and connection object for reading and writing data. You initialize it with a SQL select statement and connection object:

SqlDataAdapter daCustomers = new SqlDataAdapter(
"select CustomerID, CompanyName from Customers", conn);

The code above creates a new SqlDataAdapter, daCustomers. The SQL select statement specifies what data will be read into a DataSet. The connection object, conn, should have already been instantiated, but not opened. It is the SqlDataAdapter's responsibility to open and close the connection during Fill and Update method calls.

As indicated earlier, the SqlDataAdapter contains all of the commands necessary to interact with the data source. The code showed how to specify the select statment, but didn't show the insert, update, and delete statements. These are added to the SqlDataAdapter after it is instantiated.

There are two ways to add insert, update, and delete commands: via SqlDataAdapter properties or with a SqlCommandBuilder. In this lesson, I'm going to show you the easy way of doing it with the SqlCommandBuilder. In a later lesson, I'll show you how to use the SqlDataAdapter properties, which takes more work but will give you more capabilities than what the SqlCommandBuilder does. Here's how to add commands to the SqlDataAdapter with the SqlCommandBuilder:

SqlCommandBuilder cmdBldr = new SqlCommandBuilder(daCustomers);

Notice in the code above that the SqlCommandBuilder is instantiated with a single constructor parameter of the SqlDataAdapter, daCustomers, instance. This tells the SqlCommandBuilder what SqlDataAdapter to add commands to. The SqlCommandBuilder will read the SQL select statement (specified when the SqlDataAdapter was instantiated), infer the insert, update, and delete commands, and assign the new commands to the Insert, Update, and Delete properties of the SqlDataAdapter, respectively.

As I mentioned earlier, the SqlCommandBuilder has limitations. It works when you do a simple select statement on a single table. However, when you need a join of two or mor tables or must do a stored procedure, it won't work. I'll describe a work-around for these scenarios in future lessons.

Filling the DataSet

Once you have a DataSet and SqlDataAdapter instances, you need to fill the DataSet. Here's how to do it, by using the Fill method of the SqlDataAdapter:

daCustomers.Fill(dsCustomers, "Customers");

The Fill method, in the code above, takes two parameters: a DataSet and a table name. The DataSet must be instantiated before trying to fill it with data. The second parameter is the name of the table that will be created in the DataSet. You can name the table anything you want. Its purpose is so you can identify the table with a meaningful name later on. Typically, I'll give it the same name as the database table. However, if the SqlDataAdapter's select command contains a join, you'll need to find another meaningful name.

The Fill method has an overload that accepts one parameter for the DataSet only. In that case, the table created has a default name of "table1" for the first table. The number will be incremented (table2, table3, ..., tableN) for each table added to the DataSet where the table name was not specified in the Fill method.

Using the DataSet

A DataSet will bind with both ASP.NET and Windows forms DataGrids. Here's an example that assigns the DataSet to a Windows forms DataGrid:

dgCustomers.DataSource = dsCustomers;
dgCustomers.DataMember = "Customers";

The first thing we do, in the code above, is assign the DataSet to the DataSource property of the DataGrid. This lets the DataGrid know that it has something to bind to, but you will get a '+' sign in the GUI because the DataSet can hold multiple tables and this would allow you to expand each available table. To specify exactly which table to use, set the DataGrid's DataMember property to the name of the table. In the example, we set the name to Customers, which is the same name used as the second parameter to the SqlDataAdapter Fill method. This is why I like to give the table a name in the Fill method, as it makes subsequent code more readable.

Updating Changes

After modifications are made to the data, you'll want to write the changes back to the data base. Refer to previous discussion in the Introduction of this article on update guidance. The following code shows how to use the Update method of the SqlDataAdapter to push modifications back to the data base.

daCustomers.Update(dsCustomers, "Customers");

The Update method, above, is called on the SqlDataAdapter instance that originally filled the dsCustomers DataSet. The second parameter to the Update method specifies which table, from the DataSet, to update. The table contains a list of records that have been modified and the Insert, Update, and Delete properties of the SqlDataAdapter contain the SQL statements used to make data base modifications.

Putting it All Together

Until now, you've seen the pieces required to implement disconnected data managment. What you really need is to see all this implemented in an application. Listing 1 shows how the code from all the previous sections is used in a working program that has been simplified to enhance the points of this lesson:

Listing 1: Implementing a Disconnected Data Management Strategy

using System;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Windows.forms;

class DisconnectedDataform : form
{
 private SqlConnection  conn;
 private SqlDataAdapter daCustomers;

 private DataSet  dsCustomers;
 private DataGrid dgCustomers;

 private const string tableName = "Customers";

 // initialize form with DataGrid and Button
 public DisconnectedDataform()
 {
  // fill dataset
  Initdata();

  // set up datagrid
  dgCustomers = new DataGrid();
  dgCustomers.Location = new Point(5, 5);
  dgCustomers.Size = new Size(
   this.Clientrectangle.Size.Width - 10,
   this.Clientrectangle.Height - 50);
  dgCustomers.DataSource = dsCustomers;
  dgCustomers.DataMember = tableName;

  // create update button
  Button btnUpdate = new Button();
  btnUpdate.Text = "Update";
  btnUpdate.Location = new Point(
   this.Clientrectangle.Width/2 - btnUpdate.Width/2,
   this.Clientrectangle.Height - (btnUpdate.Height + 10));
  btnUpdate.Click += new EventHandler(btnUpdateClicked);

  // make sure controls appear on form
  Controls.AddRange(new Control[] { dgCustomers, btnUpdate });
 }

 // set up ADO.NET objects
 public void Initdata()
 {
  // instantiate the connection
  conn = new SqlConnection(
   "Server=(local);DataBase=Northwind;Integrated Security=SSPI");
  
  // 1. instantiate a new DataSet
  dsCustomers = new DataSet();

  // 2. init SqlDataAdapter with select command and connection
  daCustomers = new SqlDataAdapter(
   "select CustomerID, CompanyName from Customers", conn);

  // 3. fill in insert, update, and delete commands
  SqlCommandBuilder cmdBldr = new SqlCommandBuilder(daCustomers);
  
  // 4. fill the dataset
  daCustomers.Fill(dsCustomers, tableName);
 }

 // Update button was clicked
 public void btnUpdateClicked(object sender, EventArgs e)
 {
  // write changes back to DataBase
  daCustomers.Update(dsCustomers, tableName);
 }

 // start the Windows form
 static void Main()
 {
  Application.Run(new DisconnectedDataform());
 }
}

The Initdata method in Listing 1 contains the methods necessary to set up the SqlDataAdapter and DataSet. Notice that various data objects are defined at class level so they can be used in multiple methods. The DataGrid's DataSource property is set in the constructor. Whenever a user clicks the Update button, the Update method in the btnUpdateClicked event handler is called, pushing modifications back to the data base.

Summary

DataSets hold multiple tables and can be kept in memory and reused. The SqlDataAdapter enables you to fill a DataSet and Update changes back to the data base. You don't have to worry about opening and closing the SqlConnection because the SqlDataAdapter does it automatically. A SqlCommandBuilder populates insert, update, and delete commands based on the SqlDataAdapter's select statement. Use the Fill method of the SqlDataAdapter to fill a DataSet with data. Call the SqlDataAdapter's Update method to push changes back to a data base.

Lesson 04: Reading Data with the SqlDataReader

2008-08-13T06:01:00.000-07:00

This lesson explains how to read data with a SqlDataReader object. Here are the objectives of this lesson:

Learn what a SqlDataReader is used for.
Know how to read data using a SqlDataReader.
Understand the need to close a SqlDataReader.

Introduction

A SqlDataReader is a type that is good for reading data in the most efficient manner possible. You can *not* use it for writing data. SqlDataReaders are often described as fast-forward firehose-like streams of data.

You can read from SqlDataReader objects in a forward-only sequential manner. Once you've read some data, you must save it because you will not be able to go back and read it again.

The forward only design of the SqlDataReader is what enables it to be fast. It doesn't have overhead associated with traversing the data or writing it back to the data source. Therefore, if your only requirement for a group of data is for reading one time and you want the fastest method possible, the SqlDataReader is the best choice. Also, if the amount of data you need to read is larger than what you would prefer to hold in memory beyond a single call, then the streaming behavior of the SqlDataReader would be a good choice.

Note: Observe that I used the term "one time" in the previous paragraph when discussing the reasons why you would use a SqlDataReader. As with anything, there are exceptions. In many cases, it is more efficient to use a cached DataSet. While caching is outside the scope of this tutorial, we will discuss using DataSet objects in the next lesson.

Creating a SqlDataReader Object

Getting an instance of a SqlDataReader is a little different than the way you instantiate other ADO.NET objects. You must call ExecuteReader on a command object, like this:

SqlDataReader rdr = cmd.ExecuteReader();

The ExecuteReader method of the SqlCommand object, cmd , returns a SqlDataReader instance. Creating a SqlDataReader with the new operator doesn't do anything for you. As you learned in previous lessons, the SqlCommand object references the connection and the SQL statement necessary for the SqlDataReader to obtain data.

Reading Data

previous lessons contained code that used a SqlDataReader, but the discussion was delayed so we could focus on the specific subject of that particular lesson. This lesson builds from what you've seen and explains how to use the SqlDataReader.

As explained earlier, the SqlDataReader returns data via a sequential stream. To read this data, you must pull data from a table row-by-row. Once a row has been read, the previous row is no longer available. To read that row again, you would have to create a new instance of the SqlDataReader and read through the data stream again.

The typical method of reading from the data stream returned by the SqlDataReader is to iterate through each row with a while loop. The following code shows how to accomplish this:

 while (rdr.Read())
 {
  // get the results of each column
  string contact = (string)rdr["ContactName"];
  string company = (string)rdr["CompanyName"];
  string city    = (string)rdr["City"];

  // print out the results
  Console.Write("{0,-25}", contact);
  Console.Write("{0,-20}", city);
  Console.Write("{0,-25}", company);
  Console.WriteLine();
 }

Notice the call to Read on the SqlDataReader, rdr, in the while loop condition in the code above. The return value of Read is type bool and returns true as long as there are more records to read. After the last record in the data stream has been read, Read returns false.

In previous lessons, we extracted the first column from the row by using the SqlDataReader indexer, i.e. rdr[0]. You can extract each column of the row with a numeric indexer like this, but it isn't very readable. The example above uses a string indexer, where the string is the column name from the SQL query (the table column name if you used an asterisk, *. String indexers are much more readable, making the code easier to maintain.

Regardless of the type of the indexer parameter, a SqlDataReader indexer will return type object. This is why the example above casts results to a string. Once the values are extracted, you can do whatever you want with them, such as printing them to output with Console type methods.

Finishing Up

Always remember to close your SqlDataReader, just like you need to close the SqlConnection. Wrap the data access code in a try block and put the close operation in the finally block, like this:

 try
 {
  // data access code
 }
 finally
 {
  // 3. close the reader
  if (rdr != null)
  {
   rdr.Close();
  }

  // close the connection too
 }

The code above checks the SqlDataReader to make sure it isn't null. After the code knows that a good instance of the SqlDataReader exists, it can close it. Listing 1 shows the code for the previous sections in its entirety.

Listing 1: Using the SqlDataReader

using System;
using System.Data;
using System.Data.SqlClient;

namespace Lesson04
{
 class ReaderDemo
 {
  static void Main()
  {
   ReaderDemo rd = new ReaderDemo();
   rd.SimpleRead();
  }

  public void SimpleRead()
  {
   // declare the SqlDataReader, which is used in
   // both the try block and the finally block
   SqlDataReader rdr = null;

   // create a connection object
   SqlConnection conn = new SqlConnection(
"Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");

   // create a command object
   SqlCommand cmd  = new SqlCommand(
    "select * from Customers", conn);

   try
   {
    // open the connection
    conn.Open();

    // 1.  get an instance of the SqlDataReader
    rdr = cmd.ExecuteReader();

    // print a set of column headers
    Console.WriteLine(
"Contact Name             City                Company Name");
    Console.WriteLine(
"------------             ------------        ------------");

    // 2.  print necessary columns of each record
    while (rdr.Read())
    {
     // get the results of each column
     string contact = (string)rdr["ContactName"];
     string company = (string)rdr["CompanyName"];
     string city    = (string)rdr["City"];

     // print out the results
     Console.Write("{0,-25}", contact);
     Console.Write("{0,-20}", city);
     Console.Write("{0,-25}", company);
     Console.WriteLine();
    }
   }
   finally
   {
    // 3. close the reader
    if (rdr != null)
    {
     rdr.Close();
    }

    // close the connection
    if (conn != null)
    {
     conn.Close();
    }
   } 
  }
 }
}

Summary

SqlDataReader objects allow you to read data in a fast forward-only manner. You obtain data by reading each row from the data stream. Call the Close method of the SqlDataReader to ensure there are not any resource leaks.

Lesson 03: The SqlCommand Object

2008-08-13T05:59:00.000-07:00

This lesson describes the SqlCommand object and how you use it to interact with a data base. Here are the objectives of this lesson:

Know what a command object is.
Learn how to use the ExecuteReader method to query data.
Learn how to use the ExecuteNonQuery method to insert and delete data.
Learn how to use the ExecuteScalar method to return a single value.

Introduction

A SqlCommand object allows you to specify what type of interaction you want to perform with a data base. For example, you can do select, insert, modify, and delete commands on rows of data in a data base table. The SqlCommand object can be used to support disconnected data management scenarios, but in this lesson we will only use the SqlCommand object alone. A later lesson on the SqlDataAdapter will explain how to implement an application that uses disconnected data. This lesson will also show you how to retrieve a single value from a data base, such as the number of records in a table.

Creating a SqlCommand Object

Similar to other C# objects, you instantiate a SqlCommand object via the new instance declaration, as follows:

SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);

The line above is typical for instantiating a SqlCommand object. It takes a string parameter that holds the command you want to execute and a reference to a SqlConnection object. SqlCommand has a few overloads, which you will see in the examples of this tutorial.

Querying Data

When using a SQL select command, you retrieve a data set for viewing. To accomplish this with a SqlCommand object, you would use the ExecuteReader method, which returns a SqlDataReader object. We'll discuss the SqlDataReader in a future lesson. The example below shows how to use the SqlCommand object to obtain a SqlDataReader object:

// 1. Instantiate a new command with a query and connection
SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);

// 2. Call Execute reader to get query results
SqlDataReader rdr = cmd.ExecuteReader();

In the example above, we instantiate a SqlCommand object, passing the command string and connection object to the constructor. Then we obtain a SqlDataReader object by calling the ExecuteReader method of the SqlCommand object, cmd.

This code is part of the ReadData method of Listing 1 in the Putting it All Together section later in this lesson.

Inserting Data

To insert data into a data base, use the ExecuteNonQuery method of the SqlCommand object. The following code shows how to insert data into a data base table:

// prepare command string
string insertString = @"
insert into Categories
(CategoryName, Description)
values ('Miscellaneous', 'Whatever doesn''t fit elsewhere')";

// 1. Instantiate a new command with a query and connection
SqlCommand cmd = new SqlCommand(insertString, conn);

// 2. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();

The SqlCommand instantiation is just a little different from what you've seen before, but it is basically the same. Instead of a literal string as the first parameter of the SqlCommand constructor, we are using a variable, insertString. The insertString variable is declared just above the SqlCommand declaration.

Notice the two apostrophes ('') in the insertString text for the word "doesn''t". This is how you escape the apostrophe to get the string to populate column properly.

Another observation to make about the insert command is that we explicitly specified the columns CategoryName and Description. The Categories table has a primary key field named CategoryID. We left this out of the list because SQL Server will add this field itself. trying to add a value to a primary key field, such as CategoryID, will generate an exception.

To execute this command, we simply call the ExecuteNonQuery method on the SqlCommand instance, cmd.

This code is part of the Insertdata method of Listing 1 in the Putting it All Together section later in this lesson.

Updating Data

The ExecuteNonQuery method is also used for updating data. The following code shows how to update data:

// prepare command string
string updateString = @"
update Categories
set CategoryName = 'Other'
where CategoryName = 'Miscellaneous'";

// 1. Instantiate a new command with command text only
SqlCommand cmd = new SqlCommand(updateString);

// 2. Set the Connection property
cmd.Connection = conn;

// 3. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();

Again, we put the SQL command into a string variable, but this time we used a different SqlCommand constructor that takes only the command. In step 2, we assign the SqlConnection object, conn, to the Connection property of the SqlCommand object, cmd.

This could have been done with the same constructor used for the insert command, with two parameters. It demonstrates that you can change the connection object assigned to a command at any time.

The ExecuteNonQuery method performs the update command.

This code is part of the UpdateData method of Listing 1 in the Putting it All Together section later in this lesson.

Deleting Data

You can also delete data using the ExecuteNonQuery method. The following example shows how to delete a record from a data base with the ExecuteNonQuery method:

// prepare command string
string deleteString = @"
delete from Categories
where CategoryName = 'Other'";

// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand();

// 2. Set the CommandText property
cmd.CommandText = deleteString;

// 3. Set the Connection property
cmd.Connection = conn;

// 4. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();

This example uses the SqlCommand constructor with no parameters. Instead, it explicity sets the CommandText and Connection properties of the SqlCommand object, cmd.

We could have also used either of the two previous SqlCommand constructor overloads, used for the insert or update command, with the same result. This demonstrates that you can change both the command text and the connection object at any time.

The ExecuteNonQuery method call sends the command to the data base.

This code is part of the DeleteData method of Listing 1 in the Putting it All Together section later in this lesson.

Getting Single values

Sometimes all you need from a data base is a single value, which could be a count, sum, average, or other aggregated value from a data set. Performing an ExecuteReader and calculating the result in your code is not the most efficient way to do this. The best choice is to let the data base perform the work and return just the single value you need. The following example shows how to do this with the ExecuteScalar method:

// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand("select count(*) from Categories", conn);

// 2. Call ExecuteNonQuery to send command
int count = (int)cmd.ExecuteScalar();

The query in the SqlCommand constructor obtains the count of all records from the Categories table. This query will only return a single value. The ExecuteScalar method in step 2 returns this value. Since the return type of ExecuteScalar is type object, we use a cast operator to convert the value to int.

This code is part of the GetNumberOfRecords method of Listing 1 in the Putting it All Together section later in this lesson.

Putting it All Together

For simplicity, we showed snippets of code in previous sections to demonstrate the applicable techniques . It is also useful to have an entire code listing to see how this code is used in a working program. Listing 1 shows all of the code used in this example, along with a driver in the Main method to produce formatted output.

Listing 1. SqlConnection Demo

using System;
using System.Data;
using System.Data.SqlClient;

///

///

Demonstrates how to work with SqlCommand objects
///
class SqlCommandDemo
{
SqlConnection conn;

public SqlCommandDemo()
{
// Instantiate the connection
conn = new SqlConnection(
"Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");
}

// call methods that demo SqlCommand capabilities
static void Main()
{
SqlCommandDemo scd = new SqlCommandDemo();

Console.WriteLine();
Console.WriteLine("Categories Before Insert");
Console.WriteLine("------------------------");

// use ExecuteReader method
scd.ReadData();

// use ExecuteNonQuery method for Insert
scd.Insertdata();
Console.WriteLine();
Console.WriteLine("Categories After Insert");
Console.WriteLine("------------------------------");

scd.ReadData();

// use ExecuteNonQuery method for Update
scd.UpdateData();

Console.WriteLine();
Console.WriteLine("Categories After Update");
Console.WriteLine("------------------------------");

scd.ReadData();

// use ExecuteNonQuery method for Delete
scd.DeleteData();

Console.WriteLine();
Console.WriteLine("Categories After Delete");
Console.WriteLine("------------------------------");

scd.ReadData();

// use ExecuteScalar method
int numberOfRecords = scd.GetNumberOfRecords();

Console.WriteLine();
Console.WriteLine("Number of Records: {0}", numberOfRecords);
}

///

/// use ExecuteReader method
///
public void ReadData()
{
SqlDataReader rdr = null;

try
{
// Open the connection
conn.Open();

// 1. Instantiate a new command with a query and connection
SqlCommand cmd = new SqlCommand("select CategoryName from Categories", conn);

// 2. Call Execute reader to get query results
rdr = cmd.ExecuteReader();

// print the CategoryName of each record
while (rdr.Read())
{
Console.WriteLine(rdr[0]);
}
}
finally
{
// close the reader
if (rdr != null)
{
rdr.Close();
}

// Close the connection
if (conn != null)
{
conn.Close();
}
}
}

///

/// use ExecuteNonQuery method for Insert
///
public void Insertdata()
{
try
{
// Open the connection
conn.Open();

// prepare command string
string insertString = @"
insert into Categories
(CategoryName, Description)
values ('Miscellaneous', 'Whatever doesn''t fit elsewhere')";

// 1. Instantiate a new command with a query and connection
SqlCommand cmd = new SqlCommand(insertString, conn);

// 2. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}

///

/// use ExecuteNonQuery method for Update
///
public void UpdateData()
{
try
{
// Open the connection
conn.Open();

// prepare command string
string updateString = @"
update Categories
set CategoryName = 'Other'
where CategoryName = 'Miscellaneous'";

// 1. Instantiate a new command with command text only
SqlCommand cmd = new SqlCommand(updateString);

// 2. Set the Connection property
cmd.Connection = conn;

// 3. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}

///

/// use ExecuteNonQuery method for Delete
///
public void DeleteData()
{
try
{
// Open the connection
conn.Open();

// prepare command string
string deleteString = @"
delete from Categories
where CategoryName = 'Other'";

// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand();

// 2. Set the CommandText property
cmd.CommandText = deleteString;

// 3. Set the Connection property
cmd.Connection = conn;

// 4. Call ExecuteNonQuery to send command
cmd.ExecuteNonQuery();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
}

///

/// use ExecuteScalar method
///
/// number of records
public int GetNumberOfRecords()
{
int count = -1;

try
{
// Open the connection
conn.Open();

// 1. Instantiate a new command
SqlCommand cmd = new SqlCommand("select count(*) from Categories", conn);

// 2. Call ExecuteNonQuery to send command
count = (int)cmd.ExecuteScalar();
}
finally
{
// Close the connection
if (conn != null)
{
conn.Close();
}
}
return count;
}
}

In Listing 1, the SqlConnection object is instantiated in the SqlCommandDemo structure. This is okay because the object itself will be cleaned up when the CLR garbage collector executes. What is important is that we close the connection when we are done using it. This program opens the connection in a try block and closes it in a finally block in each method.

The ReadData method displays the contents of the CategoryName column of the Categories table. We use it several times in the Main method to show the current status of the Categories table, which changes after each of the insert, update, and delete commands. Because of this, it is convenient to reuse to show you the effects after each method call.

Summary

A SqlCommand object allows you to query and send commands to a data base. It has methods that are specialized for different commands. The ExecuteReader method returns a SqlDataReader object for viewing the results of a select query. For insert, update, and delete SQL commands, you use the ExecuteNonQuery method. If you only need a single aggregate value from a query, the ExecuteScalar is the best choice.