here is my code:
Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged Dim constr As String = ConfigurationManager.ConnectionStrings("oapConnectionString").ConnectionString Using con As New SqlConnection(constr) Using cmd As New SqlCommand("SELECT [Block_Name] FROM [oap].[dbo].[ALLBLOCKS] where [District_Name]= '" + DropDownList1.SelectedValue + "'") cmd.CommandType = CommandType.Text cmd.Connection = con con.Open() GridView1.DataSource = cmd.ExecuteReader() GridView1.DataBind() con.Close() End Using End Using End Sub End Class <columns> <asp:BoundField HeaderText="Block_Name" DataField="Block_Nam ...

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