使用子查詢在同一表上左聯接

Question

select *
from (select *
    from TableO to
    where to.week='22'
    and to.year='2018'
    ) as O 
   left join TableO lto on O.user_id=lto.user_id
where O.user_id IS NULL

我對此查詢有疑問。 誰能看到錯誤是什么？

我試圖在同一張桌子上留下聯接，試圖找到這一部分：

Answer 1

這將為您提供在2018年訂購的user_id，但自第22周以來沒有訂購

select user_id 
from   TableO
where  year = 2018
group by user_id 
having max(week) <= 22

Answer 2

SELECT userid FROM TABLE1 
EXCEPT 
(SELECT userid FROM Table2 INTERSECT SELECT userid from table2)