private void btnLoadDeTai_Click(object sender, EventArgs e)
{
var dtpc = from x in dbs.PhanCongs select new { x.TenDeTai, x.NamHoc, x.HocKy };
var detai = dbs.sp_getDeTaiChuaDuocPhanCong(Convert.ToInt32(cbbHocKy.Text), Convert.ToInt32(cbbNamHoc.Text));
cbbTenDT.DataSource = detai.ToList();
cbbTenDT.DisplayMember = "TenDT";
}