mybatisPlus-wrapper使用

创建测试类

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.plus.mybatis.mapper.UserMapper;
import com.plus.mybatis.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;

@SpringBootTest
public class WrapperTest {
    @Autowired
    private UserMapper userMapper;
}

测试

    @Test
        //查询条件全部
    void contextLoads() {
      //查询name不为空，邮箱不为空，年龄大于15
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.isNotNull("name");
        queryWrapper.isNotNull("email");
        queryWrapper.ge("age","15");
        userMapper.selectList(queryWrapper).forEach(System.out::println);
    }

    @Test
     void test2(){
        //查询名字一条记录
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.eq("name","洋");
        User user = userMapper.selectOne(wrapper);//查询一个用One
        System.out.println(user);
    }
    @Test
    void test3(){
        //查询年龄在10-100
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.between("age","10","100");
         Integer count = userMapper.selectCount(wrapper);//查询一个用One
        System.out.println(count);
        
    }

    @Test
    void test4(){
        //查询年龄在名字中有d
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper
                .notLike("name","d");
               // .likeRight("email",4); 右查询  左%e%右
       List<Map<String,Object>>maps = userMapper.selectMaps(wrapper);
       maps.forEach(System.out::println);
    }

    @Test
    void test5(){
       //模糊查询
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.inSql("id","select id from user where id<3");
        List<Object>objects = userMapper.selectObjs(wrapper);
        objects.forEach(System.out::println);
    }

    @Test
    void test6(){
        //通过ID排序
        QueryWrapper<User> wrapper = new QueryWrapper<>();
        wrapper.orderByDesc("id");


        List<User>users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }