private void btnAdd_Click(object sender, EventArgs e)
{
if (btnAdd.Text == "Thêm")
{
HangHoa hangHoa = GetDataFromDialog();
hangHoa.SaveToDatabase();
}
else
{
HangHoa hangHoa = GetDataFromDialog();
hangHoa.UpdateHangHoaToDatabase();
}
mainForm.LoadToDataGridView();
this.Close();
}