private void txtMaSP_TextChanged(object sender, EventArgs e) { if (SanPhamBUS.DanhSachSPTheoMa(txtMaSP.Text).Rows.Count > 0) { foreach (DataRow row in SanPhamBUS.DanhSachSPTheoMa(txtMaSP.Text).Rows) { txtTenSP.Text = row["TenSanPham"].ToString(); } } else { txtTenSP.ResetText(); txtSoLuong.ResetText(); } }