java - JPA 查询 "Set does NOT contain a certain item"

Question

假设我们有一个类 Person其中包含 Set<Book> books .

要查找所有拥有《Effective Java》一书的人，您可以这样写:

select p from Person p left outer join fetch p.books as b where b.name='Effective Java'

现在，我怎样才能扭转这个查询，并找到所有 Person 没有这本书？

select p from Person p "where p.books does not contain book b where b.name='Effective Java'"

Answer 1

您可以利用NOT EXISTS关键字:

select p 
from Person p
where not exists (
   select b from p.books b where b.name = 'Effective Java'
)