在JPA中使用GROUP BY

Luc*_*uke 7 java jpa java-ee

我在Question实体和Category实体之间有@ManyToMany关系.我想计算每个类别中的问题数量.我该怎么办?

JB *_*zet 9

select count(question.id), category.description 
from Category category
left join category.questions question
group by category.description
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  • 它返回List <Object []>.每个Object []都有两个元素:count(作为Long)和description(作为String).见http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#queryhql-select (3认同)