Mybatis-Plus查询投影与查询条件设置过程

//查询指定字段
        //SELECT id,name,age FROM person
        //LambdaQueryWrapper<Person> lqw = new LambdaQueryWrapper<Person>();
        //lqw.select(Person::getId,Person::getName,Person::getAge);
        QueryWrapper<Person> lqw = new QueryWrapper<Person>();
        lqw.select("id","name","age","tel");
        List<Person> personList = personDao.selectList(lqw);
        System.out.println(personList);

        QueryWrapper<Person> lqw = new QueryWrapper<Person>();
        //lqw.select("count(*) as count");
        //SELECT count(*) as count FROM user
        //lqw.select("max(age) as maxAge");
        //SELECT max(age) as maxAge FROM user
        //lqw.select("min(age) as minAge");
        //SELECT min(age) as minAge FROM user
        //lqw.select("sum(age) as sumAge");
        //SELECT sum(age) as sumAge FROM user
        lqw.select("avg(age) as avgAge");
        //SELECT avg(age) as avgAge FROM user
        List<Map<String, Object>> personList = personDao.selectMaps(lqw);
        System.out.println(personList);

//分组查询
        QueryWrapper<Person> lqw = new QueryWrapper<Person>();
        lqw.select("count(*) as count,tel");
        lqw.groupBy("tel");
        List<Map<String, Object>> personList = personDao.selectMaps(lqw);
        System.out.println(personList);

        LambdaQueryWrapper<Person> lqw = new LambdaQueryWrapper<Person>();
        lqw.eq(Person::getName, "李四").eq(Person::getPassword, "3256");
        Person loginPerson = personDao.selectOne(lqw);
        System.out.println(loginPerson);

        LambdaQueryWrapper<Person> lqw = new LambdaQueryWrapper<Person>();
        lqw.between(Person::getAge,13,17);
        List<Person> personList = personDao.selectList(lqw);
        System.out.println(personList);

        LambdaQueryWrapper<Person> lqw = new LambdaQueryWrapper<Person>();
        lqw.likeRight(Person::getName,"T");
        List<Person> personList = personDao.selectList(lqw);
        System.out.println(personList);

        LambdaQueryWrapper<Person> lqw = new LambdaQueryWrapper<>();
        lqw.orderBy(true,false, Person::getId);
        List<Person> personList = personDao.selectList(lqw);
        System.out.println(personList);