I dont know why the community dint gave any response but here is the solution-
SPQuery query = new SPQuery();
query.ViewFieldsOnly = true;
query.ViewFields = "<fieldref name="Project_x0020_Name" />";
using (SPSite site = new SPSite(SPContext.Current.Web.Url))
{
using (SPWeb web = site.OpenWeb())
{
SPList list = web.Lists["Project"];
if (list != null)
{
DataTable dt = new DataTable();
dt = list.GetItems(query).GetDataTable();
DropDownList1.DataSource = dt;
DropDownList1.DataValueField = "Project_x0020_Name";
DropDownList1.DataTextField = "Project_x0020_Name";
DropDownList1.DataBind();
DropDownList1.Items.Insert(0, "--Select Project Name--");
}
}
}