private void button1_Click(object sender, EventArgs e)
{
string sql = "Select MAGD,NGAY,KLMUA,GTMUA,KLBAN,GTBAN,KLGTRONG,GTGDRONG,ROOM,DANGSH from HR.SANGIAODICH ";
this.ShowData(sql);
DGV.Update();
DGV.Refresh();
}