Create Bound Columns Dynamically

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A sample code to Create Bound Columns Dynamically- The demonstration shows the Dropdownlist poulated with the Tables in Database pubs on Page_Load event - On selection of the table from the dropdown it display the fieldnames in the listbox. - If no date is selected from the listbox the requiredfieldvalidator shows the error accordingly - As there are two buttons and the requiredfield validator should show error only when the button to show column data is clicked button showing the column names has the causevalidation = false - For multiselect of the listbox the listitem is being used.[bold]Step 1: main.aspx[/bold]


<TABLE id="Table1" style="Z-INDEX: 108; LEFT: 44px; POSITION: absolute; TOP: 24px" cellSpacing="1" cellPadding="1" width="100%" border="1"> 

<TR> 

<TD> <asp:Label id="Label1" runat="server"> Tables</asp:Label></TD> 

<TD> <asp:DropDownList id="DropDownList1" runat="server"></asp:DropDownList></TD>

 <TD> <asp:Button id="btnShow" runat="server" Text="Show Column Info" CausesValidation="False"></asp:Button></TD>

 </TR> 

<TR> 

<TD style="HEIGHT: 29px"> <asp:Label id="Label3" runat="server">Column Information</asp:Label></TD> 

<TD style="HEIGHT: 29px"> <asp:ListBox id="ListBox1" runat="server" SelectionMode="Multiple"></asp:ListBox> <asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server" ErrorMessage="Select Item(s) from List box" ControlToValidate="ListBox1"></asp:RequiredFieldValidator></TD> 

<TD style="HEIGHT: 29px"> <asp:Button id="Button1" runat="server" Text="Show Data"></asp:Button></TD> 

</TR> 

<TR>

 <TD></TD> 

<TD> <asp:DataGrid id="DataGrid1" AutoGenerateColumns="false" runat="server" Height="100px"></asp:DataGrid></TD> 

<TD></TD> 

</TR> 

</TABLE>

[bold]Step 2:main.aspx.vb[/bold]


Dim myconnection As SqlClient.SqlConnection

Dim myda As SqlClient.SqlDataAdapter

Dim ds As DataSet

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'Put user code to initialize the page here

myconnection = New SqlClient.SqlConnection("Server=localhost;uid=sa;password=;database=pubs;")

If Not Page.IsPostBack Then

     myda = New SqlClient.SqlDataAdapter("Select * from sysobjects where xtype='u'", myconnection)

     ds = New DataSet()

     myda.Fill(ds, "AllTables")

     DropDownList1.DataTextField = "name"

     DropDownList1.DataSource = ds.Tables(0)

     DropDownList1.DataBind()

End If

End Sub

Private Sub btnShow_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnShow.Click

     ListBox1.Items.Clear()

     myda = New SqlClient.SqlDataAdapter("Select * from " & DropDownList1.SelectedItem.Text, myconnection)

    ds = New DataSet()

    myda.Fill(ds, "TableName")

    Dim dc As DataColumn

    For Each dc In ds.Tables(0).Columns

        ListBox1.Items.Add(dc.ColumnName)

    Next

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

     myda = New SqlClient.SqlDataAdapter("Select * from " & DropDownList1.SelectedItem.Text, myconnection)

    ds = New DataSet()

    myda.Fill(ds, "TableName")

    Dim i As Integer

    Dim li As ListItem

    For Each li In ListBox1.Items

      If li.Selected Then

         Dim objbc As New BoundColumn()

        objbc.DataField = li.Text

        objbc.HeaderText = li.Text

        DataGrid1.Columns.Add(objbc)

        DataGrid1.DataSource = ds.Tables(0)

        DataGrid1.DataBind()

     End If

   Next

End Sub