private void btnthem_Click(object sender, EventArgs e)
{
string tenncc = txttenncc.Text;
string diachi = txtdiachi.Text;
string sdt = txtsdt.Text;
using (quanlithucungEntities1 quanli = new quanlithucungEntities1())
{
quanli.insertNCC(tenncc, diachi, int.Parse(sdt));
MessageBox.Show("đã thêm");
Formnhacungcap_Load(sender, e);
}
}