Assign Values To Database Driven Combobox

i am using ' cmbParent.SelectedItem.ToString = "ABC" ' but id not save and generate a SqlException
" Conversion failed when converting the varchar value 'ID ' to data type int. " so i want to save id value into database table, not text value.

use this, but code in c#

<asp:dropdownlist id="DropDownList1" runat="server" xmlns:asp="#unknown">
DataSourceID="SqlDataSource1" DataTextField="Name" DataValueField="ID">

<asp:sqldatasource id="SqlDataSource1" runat="server" xmlns:asp="#unknown">
ConnectionString="<%$ ConnectionStrings:Personal %>"
SelectCommand="SELECT [Name], [ID] FROM [Test_Tab]">

<asp:button id="Button1" runat="server" text="Button" onclick="Button1_Click" xmlns:asp="#unknown">

in code file

protected void Button1_Click(object sender, EventArgs e)
{
Response.Write(DropDownList1.SelectedValue);
}