MyBatis-Plus条件构造器及常用接口查询方式汇总

一、环境搭建

1、springboot

2、jdk

3、mybatis-plus

4、mysql

5、lombok

二、测试用例

1、ge、gt、le、lt、isNull、isNotNull

@Test
public void testQuery() {
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.isNull("name")
            .ge("age",12)
            .isNotNull("email");
    int result = userMapper.delete(queryWrapper);
    System.out.println("delete return count = " + result);
}

2、eq、ne

@Test
public void testSelectOne() {
	QueryWrapper<User>queryWrapper = newQueryWrapper<>();
	queryWrapper.eq("name", "Tom");
	Useruser = userMapper.selectOne(queryWrapper);//只能返回一条记录，多余一条则抛出异常
	System.out.println(user);
}

3、between、notBetween

@Test
public void testSelectCount() {
    QueryWrapper<User>queryWrapper = newQueryWrapper<>();
    queryWrapper.between("age", 20, 30);
    Integer count = userMapper.selectCount(queryWrapper); //返回数据数量
    System.out.println(count);
}

4、like、notlike、likeLeft、likeRight

@Test
public void testSelectMaps() {
	QueryWrapper<User>queryWrapper = newQueryWrapper<>();
	queryWrapper
        .select("name", "age")
        .like("name", "e")
        .likeRight("email", "5");
	List<Map<String, Object>>maps = userMapper.selectMaps(queryWrapper);//返回值是Map列表
	maps.forEach(System.out::println);
}

5、orderBy、orderByDesc、orderByAsc

@Test
public void testSelectListOrderBy() {
	QueryWrapper<User>queryWrapper = newQueryWrapper<>();
	queryWrapper.orderByDesc("age", "id");
	List<User>users = userMapper.selectList(queryWrapper);
	users.forEach(System.out::println);
}

三、查询列表

查询方式	说明
setSqlSelect	设置 SELECT 查询字段
where	WHERE 语句，拼接 + WHERE 条件
and	AND 语句，拼接 + AND 字段=值
andNew	AND 语句，拼接 + AND (字段=值)
or	OR 语句，拼接 + OR 字段=值
orNew	OR 语句，拼接 + OR (字段=值)
eq	等于=
allEq	基于 map 内容等于=
ne	不等于<>
gt	大于>
ge	大于等于>=
lt	小于<
le	小于等于<=
like	模糊查询 LIKE
notLike	模糊查询 NOT LIKE
in	IN 查询
notIn	NOT IN 查询
isNull	NULL 值查询
isNotNull	IS NOT NULL
groupBy	分组 GROUP BY
having	HAVING 关键词
orderBy	排序 ORDER BY
orderAsc	ASC 排序 ORDER BY
orderDesc	DESC 排序 ORDER BY
exists	EXISTS 条件语句
notExists	NOT EXISTS 条件语句
between	BETWEEN 条件语句
notBetween	NOT BETWEEN 条件语句
addFilter	自由拼接 SQL
last	拼接在最后，例如：last(“LIMIT 1”)