严重：空com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：“字段列表”中的未知列“ ID”

Question

我收到以下错误：

严重：空com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：“字段列表”中的未知列“ ID”

我创建了一个表单，接受用户输入，包括名称，颜色，汽车注册，并希望将其处理并插入到具有三列的数据库中。

编码：

public class DBConnector {

// JDBC driver name and database URL                              
 static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";        
 static final String DATABASE_URL = "jdbc:mysql://localhost  /carregistration";
 Connection connection = null; // manages connection
 Statement statement = null; // query statement

public DBConnector() {

     try {
         Class.forName(JDBC_DRIVER); //Loading the java db driver
     } catch (ClassNotFoundException ex) {
         Logger.getLogger(DBConnector.class.getName()).log(Level.SEVERE, null, ex);
     }

}




 public void createConnection(){
     try {
         connection = (Connection) DriverManager.getConnection(DATABASE_URL, "root", "");

     } catch (SQLException ex) {
         Logger.getLogger(DBConnector.class.getName()).log(Level.SEVERE, null, ex);
     }
 }

 public void createStatement(){
     try {
         statement = (Statement) connection.createStatement();
     } catch (SQLException ex) {
         Logger.getLogger(DBConnector.class.getName()).log(Level.SEVERE, null, ex);
     }
 }

 public void insertCars(Cars carToInsert){
     try {
         String queryInsert = "INSERT INTO `carregistration`.`cars` (\n" +
                 "`ID` ,\n" +
                 "`CarRegistration` ,\n" +
                 "`CarOwner` ,\n" +
                 "`Color`\n" +
                 ")\n" +
                 "VALUES (\n" +
                 "NULL , '"+carToInsert.getCarRegistration()+"', '"+carToInsert.getCarOwner()+"', '"+carToInsert.getCarColor()+"'\n" +
                 "); ";

         statement.executeUpdate(queryInsert);
     } catch (SQLException ex) {
         Logger.getLogger(DBConnector.class.getName()).log(Level.SEVERE, null, ex);
     }

 }

 public void getCars(String query){

 }

 public void closeConnection(){

 }

}

public class Cars {
private String carName;
private String carOwner;
private String carColor;
private String carModel;
private String carMake;
private String carYom;
private String carRegistration;


public Cars(String carreg,String carowner,String color){
  carRegistration = carreg;
  carOwner = carowner;
  carColor = color;
}

public String getCarRegistration() {
    return carRegistration;
}

public void setCarRegistration(String carRegistration) {
    this.carRegistration = carRegistration;
}


public String getCarModel() {
    return carModel;
}

public void setCarModel(String carModel) {
    this.carModel = carModel;
}

public String getCarMake() {
    return carMake;
}

public void setCarMake(String carMake) {
    this.carMake = carMake;
}

public String getCarYom() {
    return carYom;
}

public void setCarYom(String carYom) {
    this.carYom = carYom;
}



public String getCarName() {
    return carName;
}

public void setCarName(String carName) {
    this.carName = carName;
}

public String getCarOwner() {
    return carOwner;
}

public void setCarOwner(String carOwner) {
    this.carOwner = carOwner;
}

public String getCarColor() {
    return carColor;
}

public void setCarColor(String carColor) {
    this.carColor = carColor;
}

}

具有main方法的文件也具有以下代码：

private void saveButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
    String carMake = makeCombo.getSelectedItem().toString();
    String carModel = modelCombo.getSelectedItem().toString();
    String carYOM = yomComboBox.getSelectedItem().toString();
    String carColor = colorText.getText();
    String carReg = regText.getText();
    String carFirstName = firstNameText.getText();
    String carLastName = lastNameText.getText();
    String ownerTitle = titleCombo.getSelectedItem().toString();


    try {
           //validation goes here

        if (carMake.equalsIgnoreCase("Select")) {
            JOptionPane.showMessageDialog(colorText, "Please select make and model", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (carYOM.equalsIgnoreCase("Select")) {
            JOptionPane.showMessageDialog(yomComboBox, "Please select year of manufacture", "Input Error", JOptionPane.ERROR_MESSAGE);

        } else if (carColor.trim().equalsIgnoreCase("")) {
            JOptionPane.showMessageDialog(colorText, "Please input car color", "Input Error", JOptionPane.ERROR_MESSAGE);

        } else if (!checkColor(carColor)) {

            JOptionPane.showMessageDialog(colorText, "Invalid Color", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (carReg.length() != 8) {
            JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);

        } //                else if (!match.find()) {
        //                    JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        //                }
        else if (!checkRegFirst(carReg)) {
            System.out.println("First  wrong..");
            JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (!checkRegFirstThree(carReg)) {
            System.out.println("First three wrong..");
            JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        } //                else if(checkRegFourth(carReg)) {
        //                      System.out.println("fourth three wrong..");
        //                    JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        //                }
        else if (!checkForDigits(carReg)) {
            System.out.println("digit wrong..");
            JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (!checkForLastLetter(carReg)) {
            System.out.println("last letter wrong..");
            JOptionPane.showMessageDialog(regText, "Invalid Registration", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (ownerTitle.equalsIgnoreCase("Select")) {
            JOptionPane.showMessageDialog(titleCombo, "Please Select a title", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (carFirstName.trim().equalsIgnoreCase("")) {
            JOptionPane.showMessageDialog(firstNameText, "Please input the first name", "Input Error", JOptionPane.ERROR_MESSAGE);

        } else if (carLastName.trim().equalsIgnoreCase("")) {
            JOptionPane.showMessageDialog(lastNameText, "Please input the last name", "Input Error", JOptionPane.ERROR_MESSAGE);

        } else if (!checkFirstName(carFirstName)) {
            JOptionPane.showMessageDialog(firstNameText, "Enter a first name", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else if (!checkLastName(carLastName)) {
            JOptionPane.showMessageDialog(lastNameText, "Enter a last name", "Input Error", JOptionPane.ERROR_MESSAGE);
        } else {
            String carOwner = carFirstName + " " + carLastName;
            Cars myCar = new Cars(carReg, carOwner, carColor);

            DBConnector myConnector = new DBConnector();
            myConnector.createConnection();
            myConnector.createStatement();
            myConnector.insertCars(myCar);
            JOptionPane.showMessageDialog(lastNameText, "Car inserted successfully", "Success", JOptionPane.INFORMATION_MESSAGE);
        }

    } catch (Exception Ex) {
        Ex.printStackTrace();
    }
}     

最后的代码包含用于验证用户条目的某些部分，但这不是我的问题的核心。 我很欣赏我的问题可能不是很清楚，但我会尽量具体。 为什么在字段中出现未知列“ ID”的错误？ 我创建的数据库（carregistration）只有三个字段-CarOwner，CarRegistration和Color，所以我不知道列ID的来源。 请帮助。 谢谢。

Answer 1

您的问题在这里：-

String queryInsert = "INSERT INTO `carregistration`.`cars` (\n" +
                 "`ID` ,\n" +
                 "`CarRegistration` ,\n" +
                 "`CarOwner` ,\n" +
                 "`Color`\n" +
                 ")\n" +
                 "VALUES (\n'"+carToInsert.getCarRegistration()+"', '"+carToInsert.getCarOwner()+"', '"+carToInsert.getCarColor()+"'\n" +
                 "); ";

只需从查询中删除列ID及其值即可，因为您的表carregistration不包含列ID，将查询更改为：-

String queryInsert = "INSERT INTO `carregistration` (`CarRegistration`,`CarOwner`,`Color`) VALUES ('"+carToInsert.getCarRegistration()+"','"+carToInsert.getCarOwner()+"','"+carToInsert.getCarColor()+"')";