QueryWrapper LambdaQueryWrapper LambdaQueryChainWrapper 

        SqlSessionFactory sqlSessionFactory = Util.getSqlSessionFactory();
        SqlSession session = sqlSessionFactory.openSession(true);
        UserMapper userMapper = session.getMapper(UserMapper.class);

        User user = new User(1,"cat",3);
        userMapper.insert(user);
        user = new User(2,"tiger",7);
        userMapper.insert(user);
        user = new User(3,"dog",5);
        userMapper.insert(user);

        List users = userMapper.selectList(null);
        for(User item:users){
            System.out.println(item);
        }

        QueryWrapper queryWrapper = new QueryWrapper<>();
        // %hello%
        queryWrapper.like("user_name","hello");
        userMapper.selectList(queryWrapper);

        queryWrapper = new QueryWrapper<>();
        // %hello
        queryWrapper.likeLeft("user_name","hello");
        userMapper.selectList(queryWrapper);

        queryWrapper = new QueryWrapper<>();
        // hello%
        queryWrapper.likeRight("user_name","hello");
        userMapper.selectList(queryWrapper);

        queryWrapper = new QueryWrapper<>();
        queryWrapper.between("age",1,10);
        queryWrapper.or();
        queryWrapper.eq("user_name","tiger");
        queryWrapper.orderByAsc("age");
        // age BETWEEN ? AND ? OR user_name = ?
        userMapper.selectList(queryWrapper);

        // LambdaQueryWrapper
        LambdaQueryWrapper lambdaQueryWrapper = new LambdaQueryWrapper<>();
        // 避免写错字段名
        lambdaQueryWrapper.eq(User::getName,"tiger");
        user = userMapper.selectOne(lambdaQueryWrapper);
        System.out.println(user);

        // LambdaQueryChainWrapper
        user = new LambdaQueryChainWrapper<>(userMapper)
                .eq(User::getName, "cat")
                .one();
        System.out.println(user);


        session.close();


SELECT user_id AS id,user_name AS name,age FROM t_user WHERE (age BETWEEN ? AND ? OR user_name = ?) ORDER BY age ASC

SELECT user_id AS id,user_name AS name,age FROM t_user WHERE (user_name = ?)



https://gitee.com/dyyx/hellocode/blob/master/demo/mp/mp-nospring-demo/src/main/java/com/dyyx/nospring/QueryWrapperDemo.java