create dropdown in datatable csharp dynamically

                
                        DataTable dtt1 = (DataTable)Session["dbasecolumns"];
int l = dtt1.Columns.Count;
string[] sqlcolumn = new string[l];
DropDownList drd = new DropDownList();
foreach (String colname in sqlcolumn)
{
    drd.Items.Add(colname);
}