我想在标签集中找到包含所有给定标签的项目.
I want to find the items that contain all the given tags in their tags set.
以下是简化的类:
@Entity class Item { @ManyToMany var tags: java.util.Set[Tag] = new java.util.HashSet[Tag]() } @Entity class Tag { @ManyToMany(mappedBy="tags") var items: java.util.Set[Item] = new java.util.HashSet[Item] }如果我像这样尝试
select distinct i from Item i join i.tags t where t in (:tags)我得到包含任何给定标签的项目.这并不奇怪,但我想要包含 all 给定标签的项目.所以我反过来试试:
I get the items that contain any of the given tags. That is not surprising, but I want Items that contain all of the given tags. So I try it the other way around:
select distinct i from Item i join i.tags t where (:tags) in t我收到错误消息 org.hibernate.exception.SQLGrammarException:行 IN 的参数必须全部是行表达式.如果 tags 只包含一个标签,它会起作用,但如果超过这个标签,它就会失败.
I get the error message org.hibernate.exception.SQLGrammarException: arguments of row IN must all be row expressions. It works if tags contains only a single tag, but it fails with more than that.
如何在 JPQL 中表达这一点?
How can I express this in JPQL?
推荐答案诀窍是使用计数:
select i from Item i join i.tags t where t in :tags group by i.id having count(i.id) = :tagCount更多推荐
使用 jpql 查找包含给定集合的所有元素的集合的项目
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