在HQL中使用內部聯接的子查詢

Question

我想在評級表中打印具有外鍵Movie_id的Movies表中的標題。在評級表中，我們必須根據movie_id發生得到前10個結果。因為HQL中不允許限制所以使用setMaxResults

Query q=session.createQuery("select Title from Movies  as M Inner Join ( SELECT Movie_id, COUNT(*)  FROM Rating  GROUP BY Movie_id ORDER BY COUNT(*) DESC LIMIT 10 ) as R ON M.Movie_id=R.Movie_id").setMaxResults(10);

例外情況是：

java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: ( near line 1, column 59 [select Title from com.rahul.model.Movies  as M Inner Join ( SELECT Movie_id, COUNT(*)  FROM com.rahul.model.Rating  GROUP BY Movie_id ORDER BY COUNT(*) DESC LIMIT 10 ) as R ON M.Movie_id=R.Movie_id]

既然HQL不支持子查詢怎么實現呢？

Answer 1

您可以將此查詢編寫為JOIN / GROUP BY ：

select m.Title
from Movies m Inner Join
     Rating r
     on m.Movie_id = r.Movie_id
group by m.Movie_Id, m.Title
order by count(*) desc
limit 10;

Answer 2

解決

Query q=session.createQuery("select m.title from Movies m Inner Join Rating r on m.movie_id = r.movie_id group by m.movie_id, m.title order by count(*) desc").setMaxResults(10);