private void LoadCBDVTinh()
{
tblmathangBL ctr = new tblmathangBL();
DataTable dt = new DataTable();
dt = ctr.GetDonViTinh();
cbDonVi.DataSource = dt;
cbDonVi.DisplayMember = "donvi";
cbDonVi.ValueMember = "donvi";
}