jdbc 连接数据库学习

    String url="jdbc:mysql://127.0.0.1:3306/pm?useUnicode=true&characterEncoding=utf8mb4&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8";
    String user="root";
    String password="root";
    try{
        //加载驱动
        Class.forName("com.mysql.jdbc.Driver");
        //创建连接
       Connection conn= DriverManager.getConnection(url,user,password);
        //预编译执行器
        PreparedStatement ps= conn.prepareStatement("select * from dept_table");
       //获取结果集
        ResultSet rs= ps.executeQuery();//查询
       // ps.executeUpdate();增删改
        while(rs.next()){
          int deptnum= rs.getInt("department_number");
            System.out.println(deptnum);
        }
//    rs.close();
//    ps.close();
//    conn.close();
    }catch (Exception ex){
        ex.printStackTrace();

    }finally {
Statement statement = connection.createStatement();
    }