[英]JPQL query: selecting a single Boolean which is the AND of two of object's fields
[英]JPQL (with Hibernate) adding fields to query, which are not desired
我有以下實體結構。
Venue -- n:1 -- Schedule -- 1:n -- Event
我有一個查詢來獲取場地中所有日程表的計數:
SELECT v, count(s.event) FROM Venue v
LEFT JOIN i.schedule s
GROUP BY i.id ORDER BY count(s.event) asc;
問題在於此查詢將永遠不會輸出事件為零的場所。 問題在於Hibernate,它生成以下內容:
select ..., count(schedule4_.event_id) as col_7_0_
from Venue venue0_
left outer join event_schedule schedule4_ on venue0_.id=schedule4_.venue_id,
Event event5_
where schedule4_.event_id=event5_.id and ...
您可以看到,即使我沒有要求,Hibernate也會嘗試按Schedule
加入Event
。 顯然,如果Schedule
不存在,則加入Event
毫無意義。
(我簡化了查詢,如果有錯字,則對問題不會有任何影響)。
請嘗試以下查詢:
select v.id, count(e.id) from Venue v
left join v.schedule s
left join s.events e
group by v.id order by count(e.id) asc;
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.