条件表达式中的数据类型不匹配

Question

I have a windows service which inserts data into some tables. It does so fine when in debug mode, but when I install it says "Data type mismatch in criteria expression." for every insert.

                        query = "INSERT INTO printers (" +
                            "hostname," +
                            "ip_address," +
                            "model," +
                            "picture_id," +
                            "connect_type," +
                            "status," +
                            "product_number," +
                            "Floor_ID," +
                            "print_corner," +
                            "serial_number," +
                            "printer_features" +
                            ") VALUES ('" +
                            exp.Devices[i].HostName.ToString() + "', '" +
                            exp.Devices[i].IpAddress.ToString() + "', '" +
                            exp.Devices[i].Model.ToString() + "', '" +
                            exp.Devices[i].PictureId.ToString() + "', '" +
                            exp.Devices[i].ConnectType.ToString() + "', '" +
                            exp.Devices[i].Status.ToString() + "', '" +
                            exp.Devices[i].ProductNumber.ToString() + "', '" +
                            exp.Devices[i].Floor.ToString() + "', '" +
                            exp.Devices[i].PrintCorner.ToString() + "', '" +
                            exp.Devices[i].SerialNumber.ToString() + "', '" +
                            exp.Devices[i].PrinterFeatures.ToString() +
                            "')";


        connectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + confParams.MpaSearchDatabase;

        OleDbConnection conn = new OleDbConnection(connectionString);
                        OleDbCommand myCommand = new OleDbCommand(query);
                        myCommand.Connection = conn;
                        conn.Open();
                        myCommand.ExecuteNonQuery();
                        conn.Close();
                        insertedPrintersCount = insertedPrintersCount + 1;

                        Utils.Logger.Info("Device inserted: " + exp.Devices[i].HostName);

help!

Answer 1

The data type mismatch error indicates the query is expecting data of one type but you're providing another. This query expression is passing every value as a string literal but several columns indicate they are likely a numerical value. ProductNumber and SerialNumber for example.

In order to pass the values correctly (and prevent easy injection attacks) you'll want to use the OleDbCommand class to build up the call with values of the correct type. Then let the underlying infrastructure translate it to the appropriate values.