spring boot+mybatis-plus wrapper条件构造器

问题描述

1、基本配置看我的上一篇博客

https://blog.csdn.net/weixin_41463944/article/details/126453544?spm=1001.2014.3001.5501

2、测试代码

package com.example.springbootmybatisplus;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.springbootmybatisplus.mapper.UserMapper;
import com.example.springbootmybatisplus.pojo.User;
import com.example.springbootmybatisplus.pojo.UserScoreMap;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;
import java.util.Map;

@SpringBootTest
public class WrapperTest {
    @Autowired
    private UserMapper userMapper;
    //入门
    @Test
    void contextLoads() {
        //查询name不为空的用户，并且邮箱不为空的用户，并且年龄大于等于12岁的
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper
                .isNotNull("name")
                .isNotNull("email")
                .ge("age",40);
        List<User> users = userMapper.selectList(wrapper);
        System.out.println(users);
    }

    @Test
    void test2(){
        //查询名字等于第四十
        QueryWrapper<User> wrapper = new QueryWrapper<>();
//        wrapper.ge("id",8);
//        wrapper.le("id",13);
        List<User> users = userMapper.selectList(wrapper);
        //User user = userMapper.selectOne(wrapper);
        System.out.println(users);
    }
    @Test
    void test3(){
        //查询用户年龄在20-30之间的
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.between("age",20,30);
        Integer count = userMapper.selectCount(wrapper);
        System.out.println("数量");
        System.out.println(count);
    }
    //模糊查询
    @Test
    void test4(){
        //名字中不包含四十的
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        //左和右 %e e%
        wrapper
                .notLike("name","四十")
                .likeRight("email","t");
        List<Map<String, Object>> maps = userMapper.selectMaps(wrapper);
        System.out.println(maps);
    }

    @Test
    void test5(){
        //id在子查询中查出来
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.inSql("id","select id from user where id < 5");
        List<Object> objects = userMapper.selectObjs(wrapper);
        System.out.println(objects);
    }

    @Test
    void test6(){
        //排序 id降序
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByDesc("id");
        List<User> users = userMapper.selectList(wrapper);
        System.out.println(users);
    }
    @Test
    void test7(){
        List<UserScoreMap> result=userMapper.userScoreList();
        System.out.println("联查结果");
        System.out.println(result);
    }
}

3、整理笔记位置

解决方法

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