jdbc aumentar y cambiar el código semiacabado de verificación

package daolmpl;

import java.sql.*;

public class joinDaoImpl {
    
    
    //insert

    public int insert(String name, int age, int score) {
    
    
        Connection con = null;
        PreparedStatement pst = null;
        try {
    
    
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");//注册数据库的驱动
            //获取数据库连接

            con = DriverManager.getConnection("jdbc:mysql://localhost:3506/join?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8", "root", "123456");
            con.setAutoCommit(false);

            pst = (PreparedStatement) con.createStatement();

            String sql = "insert into join-student values(?,?,?);";
            pst.setString(1, name);
            pst.setInt(2, age);
            pst.setInt(3, score);
            int i = pst.executeUpdate();

            return i;
        } catch (ClassNotFoundException e) {
    
    
            e.printStackTrace();
        } catch (SQLException e) {
    
    
            try {
    
    
                con.rollback();
            } catch (SQLException ex) {
    
    
                ex.printStackTrace();
            }
            e.printStackTrace();
        } finally {
    
    
            try {
    
    
                pst.close();
            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }
            try {
    
    
                con.close();

            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }
            return -1;
        }


    }

    //update
    public int update(int id, int score) {
    
    
        Connection con = null;
        PreparedStatement pst = null;
        try {
    
    
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");//注册数据库的驱动
            //获取数据库连接

            con = DriverManager.getConnection("jdbc:mysql://localhost:3506/join?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8", "root", "123456");
            con.setAutoCommit(false);

            pst = (PreparedStatement) con.createStatement();
            String sql = "update join-student set grade=? where id=?";
            pst.setInt(1, id);
            pst.setInt(2, score);
            int i = pst.executeUpdate();

            return i;
        } catch (ClassNotFoundException e) {
    
    
            e.printStackTrace();
        } catch (SQLException e) {
    
    
            try {
    
    
                con.rollback();
            } catch (SQLException ex) {
    
    
                ex.printStackTrace();
            }
            e.printStackTrace();
        } finally {
    
    
            try {
    
    
                pst.close();
            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }
            try {
    
    
                con.close();

            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }
            return -1;
        }


    }

    //select
    public void select() {
    
    
        Connection con = null;
        PreparedStatement pst = null;
        try {
    
    
            //加载驱动
            Class.forName("com.mysql.jdbc.Driver");//注册数据库的驱动
            //获取数据库连接

            con = DriverManager.getConnection("jdbc:mysql://localhost:3506/join?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8", "root", "123456");
            con.setAutoCommit(false);

            pst = (PreparedStatement) con.createStatement();
            String sql = "select * from student";
            //执行sql语句
            ResultSet resultSet = pst.executeQuery();
            while (resultSet.next()) {
    
    //如果有下一条记录
                String id = resultSet.getString("id");//根据列名返回值
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");
                int score = resultSet.getInt("score");
                System.out.println(id + "\t" + "name" + "\t" + age + "\t" + score);

            }
        } catch (ClassNotFoundException e) {
    
    
            e.printStackTrace();
        } catch (SQLException e) {
    
    
            try {
    
    
                con.rollback();
            } catch (SQLException ex) {
    
    
                ex.printStackTrace();
            }
            e.printStackTrace();
        } finally {
    
    
            try {
    
    
                pst.close();
            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }
            try {
    
    
                con.close();

            } catch (SQLException e) {
    
    
                e.printStackTrace();
            }

        }


    }
}