java实现学生成绩管理系统数据库

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBConnection {
    private static final String URL = "jdbc:mysql://localhost:3306/student_db";
    private static final String USER = "root";
    private static final String PASSWORD = "password";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class StudentDAO {
    public void addStudent(Student student) throws SQLException {
        String sql = "INSERT INTO Student (StudentID, Name, Gender, Grade, Class) VALUES (?, ?, ?, ?, ?)";
        try (Connection conn = DBConnection.getConnection();
             PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, student.getStudentID());
            pstmt.setString(2, student.getName());
            pstmt.setString(3, student.getGender());
            pstmt.setString(4, student.getGrade());
            pstmt.setString(5, student.getClassName());
            pstmt.executeUpdate();
        }
    }

    public Student getStudentById(String studentID) throws SQLException {
        String sql = "SELECT * FROM Student WHERE StudentID = ?";
        try (Connection conn = DBConnection.getConnection();
             PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, studentID);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                return new Student(
                    rs.getString("StudentID"),
                    rs.getString("Name"),
                    rs.getString("Gender"),
                    rs.getString("Grade"),
                    rs.getString("Class")
                );
            }
        }
        return null;
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class GradeDAO {
    public void addGrade(Grade grade) throws SQLException {
        String sql = "INSERT INTO Grade (StudentID, CourseID, Score) VALUES (?, ?, ?)";
        try (Connection conn = DBConnection.getConnection();
             PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, grade.getStudentID());
            pstmt.setString(2, grade.getCourseID());
            pstmt.setDouble(3, grade.getScore());
            pstmt.executeUpdate();
        }
    }

    public Grade getGradeByStudentAndCourse(String studentID, String courseID) throws SQLException {
        String sql = "SELECT * FROM Grade WHERE StudentID = ? AND CourseID = ?";
        try (Connection conn = DBConnection.getConnection();
             PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, studentID);
            pstmt.setString(2, courseID);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                return new Grade(
                    rs.getString("StudentID"),
                    rs.getString("CourseID"),
                    rs.getDouble("Score")
                );
            }
        }
        return null;
    }
}