Q: Remove parameter from sqldatasource I want to populate dropdownlist according to Date
  <asp:DropDownList ID="ddlNewJobOrder" DataTextField="name" DataValueField="value"
                                                        runat="server" AppendDataBoundItems="True" DataSourceID="NewJobOrderDS" ToolTip="New Job Order List" Width="110" AutoPostBack="True" OnSelectedIndexChanged="ddlNewJobOrder_SelectedIndexChanged">
  <asp:SqlDataSource ID="NewJobOrderDS" runat="server" SelectCommand="SELECT Ref_No as name, Job_Order_ID as value FROM Job_Order WHERE Status <> 'JO_Completed' and Delivery_Date = @jaDate1 ORDER BY Ref_No" OnSelecting="NewJobOrderDS_Selecting">
 <SelectParameters>
 <asp:ControlParameter ControlID="JADate1" Name="jaDate1" PropertyName="Text" Type="DateTime"/>                                
 </SelectParameters>


so each time Date is changing,then the DDL should be re-populate again.
SqlDataSource1.SelectParameters.Remove(SqlDataSource1.SelectParameters["jaDate"]);
            SqlDataSource1.SelectParameters.Add("jaDate", JADate2.Text);

but the above code is not working, the DDL has no response after the 1st time I populate it.

A: There must be a postback the change the content of the dropdown and the textbox wont postback on its own. So you must add a button or use javascript to postback the form after someone entered text in the textbox.
