用java和myql写一个学生选课系统

好的，学生选课系统可以分为三个主要部分：学生信息管理、课程信息管理和选课管理。以下是一个简单的Java和MySQL实现，可以供您参考：

1. 学生信息管理

创建一个名为Student的Java类，用于存储学生信息，包括学号、姓名、年龄、性别等。

public class Student {
    private int id;
    private String name;
    private int age;
    private String gender;

    public Student(int id, String name, int age, String gender) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    // getter and setter methods
}

在MySQL数据库中创建一个名为students的表，用于存储学生信息。表格包含id、name、age和gender列。

CREATE TABLE students (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    age INT,
    gender VARCHAR(10)
);

使用JDBC连接MySQL数据库，并编写代码实现学生信息的增加、删除、修改和查询操作。

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class StudentDAO {
    private Connection conn;

    public StudentDAO() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test";
            String user = "root";
            String password = "root";
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }

    public void addStudent(Student student) {
        String sql = "INSERT INTO students(id, name, age, gender) VALUES(?, ?, ?, ?)";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, student.getId());
            pstmt.setString(2, student.getName());
            pstmt.setInt(3, student.getAge());
            pstmt.setString(4, student.getGender());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void deleteStudent(int id) {
        String sql = "DELETE FROM students WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void updateStudent(Student student) {
        String sql = "UPDATE students SET name=?, age=?, gender=? WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, student.getName());
            pstmt.setInt(2, student.getAge());
            pstmt.setString(3, student.getGender());
            pstmt.setInt(4, student.getId());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public List<Student> getAllStudents() {
        List<Student> students = new ArrayList<>();
        String sql = "SELECT * FROM students";
        try {
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                String gender = rs.getString("gender");
                students.add(new Student(id, name, age, gender));
            }
            rs.close();
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return students;
    }

    public Student getStudentById(int id) {
        Student student = null;
        String sql = "SELECT * FROM students WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                String name = rs.getString("name");
                int age = rs.getInt("age");
                String gender = rs.getString("gender");
                student = new Student(id, name, age, gender);
            }
            rs.close();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return student;
    }
}

2. 课程信息管理

创建一个名为Course的Java类，用于存储课程信息，包括课程编号、课程名称、学分等。

public class Course {
    private int id;
    private String name;
    private int credit;

    public Course(int id, String name, int credit) {
        this.id = id;
        this.name = name;
        this.credit = credit;
    }

    // getter and setter methods
}

在MySQL数据库中创建一个名为courses的表，用于存储课程信息。表格包含id、name和credit列。

CREATE TABLE courses (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    credit INT
);

使用JDBC连接MySQL数据库，并编写代码实现课程信息的增加、删除、修改和查询操作。

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class CourseDAO {
    private Connection conn;

    public CourseDAO() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test";
            String user = "root";
            String password = "root";
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }

    public void addCourse(Course course) {
        String sql = "INSERT INTO courses(id, name, credit) VALUES(?, ?, ?)";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, course.getId());
            pstmt.setString(2, course.getName());
            pstmt.setInt(3, course.getCredit());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void deleteCourse(int id) {
        String sql = "DELETE FROM courses WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void updateCourse(Course course) {
        String sql = "UPDATE courses SET name=?, credit=? WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, course.getName());
            pstmt.setInt(2, course.getCredit());
            pstmt.setInt(3, course.getId());
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public List<Course> getAllCourses() {
        List<Course> courses = new ArrayList<>();
        String sql = "SELECT * FROM courses";
        try {
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int credit = rs.getInt("credit");
                courses.add(new Course(id, name, credit));
            }
            rs.close();
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return courses;
    }

    public Course getCourseById(int id) {
        Course course = null;
        String sql = "SELECT * FROM courses WHERE id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                String name = rs.getString("name");
                int credit = rs.getInt("credit");
                course = new Course(id, name, credit);
            }
            rs.close();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return course;
    }
}

3. 选课管理

创建一个名为CourseSelection的Java类，用于存储选课信息，包括学号、课程编号等。

public class CourseSelection {
    private int studentId;
    private int courseId;

    public CourseSelection(int studentId, int courseId) {
        this.studentId = studentId;
        this.courseId = courseId;
    }

    // getter and setter methods
}

在MySQL数据库中创建一个名为course_selection的表，用于存储选课信息。表格包含student_id和course_id列。

CREATE TABLE course_selection (
    student_id INT,
    course_id INT,
    PRIMARY KEY(student_id, course_id),
    FOREIGN KEY(student_id) REFERENCES students(id),
    FOREIGN KEY(course_id) REFERENCES courses(id)
);

使用JDBC连接MySQL数据库，并编写代码实现选课和退课操作。

import java.sql.*;

public class CourseSelectionDAO {
    private Connection conn;

    public CourseSelectionDAO() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test";
            String user = "root";
            String password = "root";
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }

    public void selectCourse(int studentId, int courseId) {
        String sql = "INSERT INTO course_selection(student_id, course_id) VALUES(?, ?)";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, studentId);
            pstmt.setInt(2, courseId);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void dropCourse(int studentId, int courseId) {
        String sql = "DELETE FROM course_selection WHERE student_id=? AND course_id=?";
        try {
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, studentId);
            pstmt.setInt(2, courseId);
            pstmt.executeUpdate();
            pstmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

以上是一个简单的学生选课系统的Java和MySQL实现，您可以根据自己的需要进行修改和扩展。