一对多查询（不适用默认的mybatisplus中的查询方法)

1.在entity/User中定义一个查询结果的字段；

    @TableField(exist = false) //告诉数据库这个字段是不存在
    private List bookList;  //bookList是用于额外查询的字段

2.在mapper/userMapper中创建一个方法；

//一对多查询
Page findPage(Page page);

3.在resources/mapper/Book.xml

<?xml version="1.0" encoding="UTF-8"?>



    
        
        
        
        
        
        
        

        
            
            
            
        
    

    
        SELECT `user`.* ,book.id as b_id, book.name as b_name,book.price as b_price from `user`
        left join book on user.id = book.user_id where `user`.nick_name like concat('%', #{nickName}, '%')
    

在UserController中路由分页查询中进行调用findPage

        Page userPage = userMapper.findPage(new Page<>(pageNum,pageSize) );