DetailsView + SQLDataSource How to get data from onselected

I am trying to use a DropDownList in a DetailsView for the ItemTemplate, InsertItemTemplate, and EditItemTemplate. I must bind this DropDownList to a SQL-Server support table using a function that returns a DataTable. I am not allowed to use a SQLDataSource in my backwards IT department. So, not only do I need to load the DropDownList, I also need to make the SelectedValue equal to the current record that I am viewing, editing. Any ideas how I do this? 

hi all , I am an absolute beginner and do not as such write code with any confidence yet.  I am persevering with visual developer express 2010 whilst learning visual basic from hello world stage onward. In the meantime I have a difficulty . I am trying to display a range of data in details view which is being fed a parameter from a dropdown  list. I cannot seem to come up with a query that will pull over all data from a column that is less than a certain number and then display it with distinct values in the dropdown. for example I would like say to pull over height data where it displays all data below  20m all data below 30m etc. is this possible without heavy coding? 

I have this code but dunno how to get the data from the existing sqldatasource1 into the list. Pls help to post the code. 

ie the code for this line:        ' Get Data from Database and Fill DataReader and we will pass values to List

The sqldatasource1 returns only one field of data called holiday which is a date field. Thanks

<%@ Page Title="" Language="VB" MasterPageFile="~/00_MasterPage.master" %>

<script runat="server">

    Private Function GetPublicHolidays() As List(Of DateTime)

        Dim list As New List(Of DateTime)()

        ' Get Data from Database and Fill DataReader and we will pass values to List

    End Function

   
   
    </script>

    <asp:SqlDataSource ID="SqlDataSource1" runat="server"></asp:SqlDataSource>

I have googled a relevant code for my control on ASP.net page but it get data from a har code list. How to modify the code so it get the data from the sqldatasource which I have already built instead of getting data from the list?

Thanks

protected void calDT_DayRender(object sender, DayRenderEventArgs e)

    {

        if (dtholidays.Contains(e.Day.Date))

        {

            e.Day.IsSelectable = false;

        }

    }

private List<DateTime> GetPublicHolidays()

    {

        List<DateTime> list = new List<DateTime>(); 

        //populate from database or other sources

        list.Add(new DateTime(2010, 01, 01));

        list.Add(new DateTime(2010, 02, 02));

        list.Add(new DateTime(2010, 02, 14));

        list.Add(new DateTime(2010, 03, 02));

        list.Add