'System.Data.SqlClient.SqlException'

Question

我目前在此行上收到此错误：“ System.Data.SqlClient.SqlException”：

int MemberExist = (int)check_Member.ExecuteScalar();

这是我的例外： http : //imgur.com/bnp7OcT

我正在尝试打开与数据库的连接，并从文本框中检索数据，并查看ID是否与数据库中的名字和姓氏匹配。 如果是这样，那么它将继续执行写入PDF文件的代码，如果不是，它将从文本框中输入某些代码到数据库中。 我敢肯定我的代码中还有其他错误，如果有人可以提供帮助，那将是很好的选择，但是目前我只是在寻求有关上述错误的帮助，这就是我到目前为止所拥有的：

       protected void btnSubmit_Click(object sender, EventArgs e)
        {


            string PostCode = txtPostcode.Text;
            string PostCode2 = txtDestinationPostcode.Text;

            // Get the connection 
            SqlConnection DBConnection = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=""E:\DS\Prac5\Part1\App_Data\MyDatabase.mdf"";Integrated Security=True");
            SqlDataReader Reader = null;



            DBConnection.Open();
            SqlCommand check_Member = new SqlCommand("SELECT * FROM Members WHERE MembershipID = FirstName AND LastName = @Txtnput)", DBConnection);
            check_Member.Parameters.AddWithValue("@Txtnput", txtMembershipid.Text);

          //THIS IS THE LINE BELOW I'm HAVING ISSUES WITH

            int MemberExist = (int)check_Member.ExecuteScalar();

            if (MemberExist > 0)
            {
                // if Member exists

                PostCodeInfo MatchingPostCode = Find(PostCodeList, PostCode);
                if (MatchingPostCode == null)
                {
                    lblOutput.Text = "Your postcode could not be found!";

                }
                else
                {
                    lblOutput.Text = string.Format("({0},{1})", MatchingPostCode.Locality, MatchingPostCode.State);

                }


                PostCodeInfo MatchingPostCode2 = Findtwo(PostCodeList, PostCode2);
                if (MatchingPostCode2 == null)
                {
                    lblOutput2.Text = "Your postcode could not be found!";

                }
                else
                {
                    lblOutput2.Text = string.Format("({0},{1})", MatchingPostCode2.Locality, MatchingPostCode2.State);

                }

                // Put Code here if member text = to member ID 
                // If not insert member into database


                //We keep track of our invoice number by storing it in a plain text file. Using only a variable in memory means that it resets every time our web server turns off!
                string NewInvoiceNumber = GenerateNextInvoiceNumber(InvoiceFilePath);

                //Creating a document that will be stored on the web server's hard drive
                Document MyDoc = new Document();
                string PDFPath = Server.MapPath("PDFs");
                //Name each of our PDF files uniquely using the invoice number so we don't overwrite them.
                FileStream LocalStream = new FileStream(string.Format(@"{0}\Receipt-{1}.pdf", PDFPath, NewInvoiceNumber), FileMode.Create);
                PdfWriter.GetInstance(MyDoc, LocalStream);

                //Also store the document in memory such that we can send it to the client as an array of bytes
                MemoryStream HTTPStream = new MemoryStream();
                PdfWriter.GetInstance(MyDoc, HTTPStream);

                //Creating the PDF
                MyDoc.Open();
                //Create the custom fonts we'll use in the PDF
                Font Blue = new Font(Font.FontFamily.TIMES_ROMAN, 20f, Font.NORMAL, new BaseColor(System.Drawing.Color.Blue));
                Font Grey = new Font(Font.FontFamily.TIMES_ROMAN, 12f, Font.NORMAL, new BaseColor(System.Drawing.Color.Gray));
                Font Black = new Font(Font.FontFamily.TIMES_ROMAN, 14f, Font.NORMAL, new BaseColor(System.Drawing.Color.Black));

                //We create our Title paragraph seperately because we need to specify the text alignment in order to put it in the center.
                Paragraph Title = new Paragraph("Truck delivery receipt\n", Blue);
                Title.Alignment = Element.ALIGN_CENTER;
                MyDoc.Add(Title);

                MyDoc.Add(new Paragraph(string.Format("\nProccessed on " + DateTime.Now.ToString("dd/MM/yyyy h:mm:tt."), Black)));
                MyDoc.Add(new Paragraph(string.Format("\nThank you for doing business with Truck Deliveries Co., {0} {1}", txtName.Text, txtLastName.Text)));
                MyDoc.Add(new Paragraph(string.Format("Your invoice number is {0}. ", NewInvoiceNumber, Black)));
                MyDoc.Add(new Paragraph(string.Format("Please quote this number if you contact support.\n")));
                MyDoc.Add(new Paragraph(string.Format("\n")));
                Paragraph Heading = new Paragraph("Delivery details\n", Blue);
                MyDoc.Add(Heading);
                MyDoc.Add(new Paragraph(string.Format("\n")));
                MyDoc.Add(new Paragraph(string.Format("Your delivery will arrive at {0}, after leaving for delivery at {1} ", txtDeliveryDate.Text, DateTime.Now.ToString("dd/MM/yyyy h:mm:tt."))));
                MyDoc.Add(new Paragraph(string.Format("\n")));
                MyDoc.Add(new Paragraph(string.Format("{0} truck delivery from {1}, {2} {3} to {4}, {5} {6}.", txtNumberoftrucks.Text, txtDeliveryAddress.Text, txtPostcode.Text, lblOutput.Text, txtDestinationDeliveryAddress.Text, txtDestinationPostcode.Text, lblOutput2.Text)));
                MyDoc.Add(new Paragraph(string.Format("\n")));
                MyDoc.Add(new Paragraph(string.Format("Cost of delivery:$19,830.00.")));
                MyDoc.Add(new Paragraph(string.Format("Cost of insurance:$289.87.")));
                MyDoc.Add(new Paragraph(string.Format("Cost charged (incl. GST):$22102.87. ")));
                MyDoc.Add(new Paragraph(string.Format("\n")));
                MyDoc.Add(new Paragraph(string.Format("Any queries regarding your delivery can be sent to TruckDeliver@Trucks.com, or alternatively you can call 03 9876 5432.")));
                MyDoc.Add(new Paragraph(string.Format("\n")));
                MyDoc.Add(new Paragraph(string.Format("Our business is located at 72 Kaolin Street, VIC, AU. The Fees from this truck delivery will be charged to {0}. We will contact you via the phone number 03 9876 1234 if we experience any issues with yourt order.", txtBillingAddress.Text)));

                MyDoc.Add(new Paragraph(string.Format("\n")));

                MyDoc.Close();

                //Send PDF to client via a HTTP 
                Response.ContentType = "application/pdf";
                Response.AddHeader("Content-Disposition", string.Format(@"attachment; filename=Receipt-{0}.pdf", NewInvoiceNumber));
                Response.BinaryWrite(HTTPStream.ToArray());

            }
            else
            {

                //Member doesn't exist.
                string firstname = txtName.Text;
                string lastname = txtLastName.Text;
                string query = "INSERT INTO Wines(firstname, lastname) " +
                               "Values('" + firstname + "', '" + lastname + "')";

            }

Answer 1

在查询的末尾，在@Txtnput之后，您有一个额外的括号。 它应该是：

        SqlCommand check_Member = new SqlCommand("SELECT * FROM Members WHERE MembershipID = FirstName AND LastName = @Txtnput", DBConnection);