private void txttimkiem_TextChanged(object sender, EventArgs e)
{
using (quanlithucungEntities1 quanli = new quanlithucungEntities1())
{
if (txttimkiem.Text.Trim() == "" || txttimkiem.Text.Trim() == null)
{
dgvHoaDon.DataSource = quanli.HoaDons.ToList();
}
else if (txttimkiem.Text.Trim() != "")
{
dgvHoaDon.AutoGenerateColumns = false;
dgvHoaDon.DataSource = quanli.timkiemHD(txttimkiem.Text);
}
}
}