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ASP.NET Tutorial - Advance Practical Examples on DataGrid

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Edit column in a Datagrid Control

In Example 46 ExpertDataGridEditCommandColumn.aspx there is one problem that there is no Update command execution. This example is an answer to that problem. Therefore the values here are updating using update command in the subroutine.

Example 50 ExpertDataGridEditEmployees.aspx

<%@ Import Namespace="System.Data.SqlClient" %>

<Script Runat="Server">

Dim conNorthwind As SqlConnection

Dim cmdSql As SqlCommand

Dim strSql As String

Sub Page_Load

conNorthwind=New SqlConnection( "Server=localhost; UID=sa; PWD=secret;Database=Northwind" )

If Not IsPostBack Then

BindDataGrid

End If

End Sub

Sub BindDataGrid

cmdSql = New SqlCommand( "Select * From Employees", conNorthwind )

conNorthwind.Open()

dgrdEmployees.DataSource = cmdSql.ExecuteReader() dgrdEmployees.DataBind()

conNorthwind.Close()

End Sub

Sub dgrdEmployees_EditCommand( s As Object, e As DataGridCommandEventArgs )

dgrdEmployees.EditItemIndex = e.Item.ItemIndex

BindDataGrid

End Sub

Sub dgrdEmployees_UpdateCommand( s As Object, e As DataGridCommandEventArgs )

Dim intEmployeeID As Integer

Dim txtFirstName As TextBox

Dim strFirstName As String

intEmployeeID = dgrdEmployees.DataKeys( e.Item.ItemIndex )

txtFirstName = e.Item.Cells( 1 ).Controls( 0 )

strFirstName = txtFirstName.Text

strSql = "Update Employees Set FirstName=@FirstName " _

& " Where EmployeeID=@EmployeeID"

cmdSql = New SqlCommand( strSql, conNorthwind )

cmdSql.Parameters.Add( "@FirstName", strFirstName )

cmdSql.Parameters.Add( "@EmployeeID", intEmployeeID )

conNorthwind.Open()

cmdSql.ExecuteNonQuery()

conNorthwind.Close()

dgrdEmployees.EditItemIndex = -1

BindDataGrid

End Sub

Sub dgrdEmployees_CancelCommand( s As Object, e As DataGridCommandEventArgs )

dgrdEmployees.EditItemIndex = -1

BindDataGrid

End Sub

</Script>

<html>

<head><title>ExpertDataGridEditEmployees.aspx</title></head>

<body>

<form Runat="Server">

<asp:DataGrid

ID="dgrdEmployees"

OnEditCommand="dgrdEmployees_EditCommand"

OnUpdateCommand="dgrdEmployees_UpdateCommand"

OnCancelCommand="dgrdEmployees_CancelCommand"

DataKeyField="EmployeeID"

AutoGenerateColumns="False"

CellPadding="10"

HeaderStyle-BackColor="LightGrey"

Runat="Server">

<Columns>

<asp:BoundColumn

HeaderText="Employee ID"

DataField="EmployeeID"

ReadOnly="True" />

<asp:BoundColumn

HeaderText="First Name" DataField="FirstName" />

<asp:EditCommandColumn

EditText="Edit!"

UpdateText="Update!"

CancelText="Cancel!" />

</Columns>

</asp:DataGrid>

</form>

</body>

</html>

The output of this example is shown below :

It can be seen that updation is possible.

When an item is selected for editing, the dgrdEmployees_EditCommand subroutine is executed. This subroutine sets the value od EditItemIndex property of the DataGrid. When the Update link is clicked then dgrdEmployees_UpdateCommand subroutine executes and FirstName column of employees table is updated. Each row of a DataGrid consists of cell and each cell contains controls.

After a column is updated in the database, the DataGrid control’s EditItemIndex property is assigned the value -1. Any item can be unselected by this value for editing in the DataGrid.

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