程序代码：

 private void Add_Click(object sender, EventArgs e)
        {
            if (cmbBarcode.Text == "")
                return;
            if (!chkCustomerID.Checked)
                nudDiscount.Value = 1;
             = string.Format("select ID,ISBN,Name,Price from Book where Barcode='{0}'",cmbBarcode.Text);
            SqlDataReader reader = null;



            try
            {
                reader = cmd.ExecuteReader();

                if (reader.Read())
                {
                    object[] obj = new object[7];
                    obj[0] = reader["ID"];
                    obj[1] = reader["ISBN"];
                    obj[2] = reader["Name"];
                    obj[3] = reader["Price"];
                    obj[4] = nudNumber.Value;
                    obj[5] = nudDiscount.Value;
                    obj[6] = ((int)obj[3]) * ((int)obj[4]) * ((int)obj[5]);
                    this.dataGridView1.Rows.Add(obj);
                }
                else
                {
                    MessageBox.Show("没有符合条件的记录", "提示", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
                }
            }
            catch (Exception exp)
            {
                MessageBox.Show("数据访问错误：" + exp.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            finally
            {
                if (reader != null && !reader.IsClosed)
                    reader.Close();
            }
        }

程序代码：

 reader = cmd.ExecuteReader();

                if (reader.Read())
                {
                    object[] obj = new object[7];
                    obj[0] = reader["ID"];
                    obj[1] = reader["ISBN"];
                    obj[2] = reader["Name"];
                    obj[3] = reader["Price"];
                    obj[4] = nudNumber.Value;
                    obj[5] = nudDiscount.Value;
                    obj[6] = ((int)obj[3]) * ((int)obj[4]) * ((int)obj[5]);
                    this.dataGridView1.Rows.Add(obj);