Deleting Records from Database

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The following are the steps involved in deletion of records from the database in ASP.Net:-

Instantiate the connection object.

Open a connection object, the connection object can be declared in the web.config file or in the .aspx file itself.

Pass the connection object to the command object.

Run the ExecuteNonQuery method of the command object.

Close the connection

Dispose the memory that is allocated to the connection and command object so that no memory leaks happened.

Use the try catch block for exception handling.

Example: Demonstrate Deleting record from the database using grid view control.

Web.config

<? xml version = " 1.0 " ?>

<!--

Note: As an alternative to hand editing this file you can use the

web admin tool to configure settings for your application. Use

the Website->Asp.Net Configuration option in Visual Studio.

A full list of settings and comments can be found in

machine.config.comments usually located in

\Windows\Microsoft.Net\Framework\v2.x\Config

-->

</connectionStrings>

<system.web>

<!--

Set compilation debug="true" to insert debugging

symbols into the compiled page. Because this

affects performance, set this value to true only

during development.

-->

< compilation debug = " true " />

<!--

The <authentication> section enables configuration

of the security authentication mode used by

ASP.NET to identify an incoming user.

-->

< authentication mode = " Windows " />

<!--

The <customErrors> section enables configuration

of what to do if/when an unhandled error occurs

during the execution of a request. Specifically,

it enables developers to configure html error pages

to be displayed in place of a error stack trace.

<customErrors mode="RemoteOnly"

defaultRedirect="GenericErrorPage.htm">

</customErrors>

-->

</system.web>

</configuration>

DeletingRecords.aspx

<% @ Page Language ="C#" AutoEventWireup ="true" CodeFile="DeletingRecords.aspx.cs" Inherits ="DeletingRecords" %>

<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

<strong><em> Deleting Record from Database <br/>

</em></strong>

<br/>

<asp:GridView ID ="grdCategories" runat ="server" DataSourceID = "SQLNorthwind"

DataKeyNames = "CategoryID" AutoGenerateDeleteButton ="True" AutoGenerateEditButton ="True">

</asp:GridView>

<asp:SqlDataSource ID ="SQLNorthwind" runat ="server" ConnectionString =" <% $ ConnectionStrings:northwindConnectionString %> " ProviderName ="System.Data.SqlClient" SelectCommand ="SELECT [CategoryID], [CategoryName],[Description] FROM [Categories]" UpdateCommand ="UPDATE Categories SET CategoryName=@CategoryName,Description=@Description WHERE CategoryID=@CategoryID" DeleteCommand ="DELETE Categories WHERE CategoryID=@CategoryID">