参数索引超出范围（1>参数数目，为0）。尝试将信息保存到数据库时输出

Question

我创建了一个小程序，用户必须在其中将数据输入文本字段并从组合框中选择选项。我使用XAMPP创建了一个数据库，并通过Web浏览器为该程序创建了相应的表。

数据库称为activitydb，负责存储程序数据的表称为userdata。

表中的第一列称为UserID，它是一个整数，每次添加新条目时它都会自动递增。其余所有都是具有最大长度变化的varchar。

当前是程序的源代码：

        Connection con = null;
        Statement st = null;
        try {
            // activitydb = database name
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/activitydb?zeroDateTimeBehavior=convertToNull", "root", "");
            st = con.createStatement();
            // userdata = table name
            String sqlconn = "INSERT INTO userdata (UserID, LastName, FirstName, MiddleName, Email, Sex, HomeAddress, City, CPUBrand, ComputerType, HardwareSpecs, GPUBrand, GPUType, GPUVRAM)";
            PreparedStatement prdStmt = con.prepareStatement(sqlconn);
            // Input of variable data into corresponding database table
            // First table will be declared as null as it is an Integer designed with an Auto Increment
            prdStmt.setString(1, null);
            prdStmt.setString(2, jTextLastName.getText());
            prdStmt.setString(3, jTextFirstName.getText());
            prdStmt.setString(4, jTextMiddleName.getText());
            prdStmt.setString(5, jTextEmail.getText());
            prdStmt.setString(6, jComboBoxSex.getSelectedItem().toString());
            prdStmt.setString(7, jTextHomeAddress.getText());
            prdStmt.setString(8, jTextCity.getText());
            prdStmt.setString(9, jComboBoxCPUBrand.getSelectedItem().toString());
            prdStmt.setString(10, jComboBoxComputerType.getSelectedItem().toString());
            prdStmt.setString(11, jComboBoxHardwareSpecs.getSelectedItem().toString());
            prdStmt.setString(12, jComboBoxGPUBrand.getSelectedItem().toString());
            prdStmt.setString(13, jComboBoxGPUType.getSelectedItem().toString());
            prdStmt.setString(14, jComboBoxGPUVRAM.getSelectedItem().toString());
            // Do this if something goes wrong
        } catch (SQLException err) {
            // Print error message to console for diagnosis
            System.out.println(err.getMessage());
        }

对于组合框，我使用getSelectedItem().toString()将在内部找到的数据存储为字符串。

单击按钮将使该程序除了在控制台中执行以下操作外，什么也不做：Parameter index out of range (1 > number of parameters, which is 0).

Answer 1

您缺少占位符，您的查询应该是：

String sqlconn = "INSERT INTO userdata (UserID, LastName, FirstName, MiddleName," +
        " Email, Sex, HomeAddress, City, CPUBrand, ComputerType, HardwareSpecs," +
        " GPUBrand, GPUType, GPUVRAM) " +
        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";