private void txtTenSach_TextChanged(object sender, EventArgs e) { if (SachBUS.DanhSachSachTheoTen(txtTenSach.Text).Rows.Count > 0) { foreach (DataRow row in SachBUS.DanhSachSachTheoTen(txtTenSach.Text).Rows) { txtMaSach.Text = row["MaSach"].ToString(); txtTheloai.Text = row["TenTL"].ToString(); txtTacgia.Text = row["TenTG"].ToString(); } } else { txtMaSach.ResetText(); txtTheloai.ResetText(); txtTacgia.ResetText(); txtSoLuong.ResetText(); txtGiaNhap.ResetText(); } }