java - java jSTL 中外键的 DAO Controller

Question

我有 2 张 table 要加入。第一个表名为 students，有几个字段 => (studentID、姓名、名字、性别、出生日期、地址、电话、电子邮件、状态、日期注册、许可证 ID)

我的第二个表名为 licenses，有 2 个字段 =>(licenseID、type_license)。

我的 SQL 请求似乎是正确的，如下:

SELECT students.studentID, students.name, students.firstname, students.dateofbirth, students.sex, students.address, 
students.phone, students.email, students.status, students.dateofbirth, licenses.type_license 

FROM students 

INNER JOIN licenses 

ON students.licenseID = licenses.licenseID

我认为我的模型也不错

模范学生

package com.autoecole.model;


public class Student {

    private int studentID;
    private String name;
    private String firstname;
    private String dateofbirth;
    private String sex;
    private String address;
    private String phone;
    private String email;
    private String status;
    private String dateregister;
    private int licenseID;

    public void setStudentID(int studentID) {
        this.studentID = studentID;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public void setDateofbirth(String dateofbirth) {
        this.dateofbirth = dateofbirth;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public void setDateregister(String dateregister) {
        this.dateregister = dateregister;
    }

    public void setLicenseID(int licenseID) {
        this.licenseID = licenseID;
    }
    public int getStudentID() {
        return studentID;
    }

    public String getName() {
        return name;
    }

    public String getFirstname() {
        return firstname;
    }

    public String getDateofbirth() {
        return dateofbirth;
    }

    public String getSex() {
        return sex;
    }

    public String getAddress() {
        return address;
    }

    public String getPhone() {
        return phone;
    }

    public String getEmail() {
        return email;
    }

    public String getStatus() {
        return status;
    }

    public String getDateregister() {
        return dateregister;
    }

    public int getLicenseID() {
        return licenseID;
    }   

}

模型许可证

public class License {

    private int licenseID;
    private String type_license;

    public void setLicenseID(int licenseID) {
        this.licenseID = licenseID;
    }

    public void setTypeLicense(String type_license) {
        this.type_license = type_license;
    }

    public int getLicenseID() {
        return licenseID;
    }

    public String getTypeLicense() {
        return type_license;
    }

}

在我的 getAllRecordsStudents() 方法中，此行有一条错误消息:

 studentBean.setTypeLicense(rs.getString("licenses.type_license"));

“未为 Student 类型定义 setTypeLicense(String) 方法”

public static List getAllRecordsStudents(){  
        List <Student> list=new ArrayList<Student>();  

        try{  
            Connection con=getConnection();  
            PreparedStatement ps=con.prepareStatement("SELECT students.studentID, students.name, students.firstname, students.dateofbirth, students.sex, students.address, students.phone, students.email, students.status, students.dateofbirth, licenses.type_license FROM students INNER JOIN licenses ON students.licenseID = licenses.licenseID");  
            ResultSet rs=ps.executeQuery();  
            while(rs.next()){  
                Student studentBean =new Student();  
                studentBean.setStudentID(rs.getInt("studentID"));  
                studentBean.setName(rs.getString("name"));  
                studentBean.setFirstname(rs.getString("firstname")); 
                studentBean.setDateofbirth(rs.getString("dateofbirth"));  
                studentBean.setSex(rs.getString("sex"));  
                studentBean.setAddress(rs.getString("address")); 
                studentBean.setPhone(rs.getString("phone")); 
                studentBean.setEmail(rs.getString("email")); 
                studentBean.setStatus(rs.getString("status")); 
                studentBean.setDateregister(rs.getString("dateregister")); 
                studentBean.setTypeLicense(rs.getString("licenses.type_license"));
                list.add(studentBean);  
            }  
        }catch(Exception e){System.out.println(e);}  
        return list;  
    }  

编辑:这是屏幕截图

AddStudent方法()

public static int addStudent(Student studentBean){  
        int status=0;  
        try{  
            Connection con=getConnection();  
            PreparedStatement ps=con.prepareStatement("insert into students(name, firstname, sex, dateofbirth, address, phone, email, status, dateregister, licenseID) values(?,?,?,?,?,?,?,?,?,?)");  
            ps.setString(1,studentBean.getName());   
            ps.setString(2,studentBean.getFirstname());   
            ps.setString(3,studentBean.getDateofbirth());    
            ps.setString(4,studentBean.getSex());  
            ps.setString(5,studentBean.getAddress());
            ps.setString(6, studentBean.getPhone());
            ps.setString(7, studentBean.getEmail());
            ps.setString(8, studentBean.getStatus());
            ps.setString(9, studentBean.getDateregister());
            ps.setInt(10, studentBean.getLicenseID());
            status=ps.executeUpdate();  
        }catch(Exception e){System.out.println(e);}  
        return status;  
    }

真诚地，我不明白我应该做什么？

Answer 1

使用联接，您无需在结果集查找中定义表名称，因为它会返回两个表的新 View 。

rs.getString("licenses.type_license");

将其更改为

rs.getString("type_license");

它应该可以工作。

如果可以的话，请查看运行该查询时返回的数据库中的完整表

**编辑他们是错误的类型。 type_license 在 licence 中是 String，在 Student 中是 int。

要获取解析它或更改其中一种类型所需的值。我喜欢；

studentBean.setTypeLicense(Integer.valueOf(rs.getString("type_license")));

但是您可以通过几种不同的方式来做到这一点。