private void Form1_Load(object sender, EventArgs e)
{
txtmahs.Enabled = false;
DataTable dt = new DataTable();
LopHocBUS lopBUS = new LopHocBUS();
dt = lopBUS.LoadDSLop();
cblop.DataSource = dt;
cblop.DisplayMember = "Tenlop";
cblop.ValueMember = "Malop";
HienThi();
}
void HienThi()
{
dataGridView1.DataSource = lopBUS.LoadDSLop();
}