title: Ajax combobox with asp.net
body: <p>i'm using a Combobox from AjaxControlToolkit in asp.net i'm filling this combobox with data from a database using sql Data Source, but i need to add an empty field in the combobox so in other words i need to add an empty row to the datatable but i'm using an sql data source so how can i do that ?</p>
  
  <pre><code> &lt;%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %&gt;
  
   &lt;asp:ComboBox ID="service_listt" runat="server" AutoPostBack="true" DataTextField="CL_DESCRIPTION" DataValueField="CL_ID" DataSourceID="SqlDataSource1" CssClass="RedTypeComboBoxStyle" &gt;
   &lt;/asp:ComboBox&gt;  
  </code></pre>