mybatisplus----条件查询wrapper的基本操作

直接上代码：

 

 

package com.hui;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hui.mapper.UserMapper;
import com.hui.pojo.User;
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
    UserMapper userMapper;
//下面这是条件查询
    //wrapper对象其实就是封装了一个条件，然后语句根据这个条件去执行

    @Test
    void testWrapper1() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.isNotNull("age")
                .isNotNull("id")
                .eq("age", 20);

        userMapper.selectList(wrapper).forEach(System.out::println);
    }


    @Test
    void testWrapper2() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name", "瓜瓜");
        System.out.println(userMapper.selectOne(wrapper));
    }

    @Test
    void testWrapper3() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name", "本杰明");

        Integer integer = userMapper.selectCount(wrapper);
        System.out.println(integer);


    }


    @Test
    void testWrapper4() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.likeRight("email", "t");

        List<Map<String, Object>> maps = userMapper.selectMaps(wrapper);
        maps.forEach(System.out::println);


    }

    @Test
    void testWrapper5() {

        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.inSql("id", "select id from user where id=2");
        List<Object> objects = userMapper.selectObjs(wrapper);
        objects.forEach(System.out::println);


    }

    @Test
    void testWrapper6() {
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByDesc("id");
        List<User> users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }
}