[英]JPA 2 Criteria - group by and count
我有两个实体,ShoppingCart和ShoppingCartLine。 ShoppingCart有ShoppingCartLines的集合。 我正在尝试使用条件创建JPA查询,以获取ShoppingCart ID的列表以及每个ShoppingCart具有的ShoppingCartLines的数量。
这是ShoppingCart类中的映射:
@OneToMany(mappedBy = "shoppingCart", fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval=true)
private Set<ShoppingCartLine> shoppingCartLines = new TreeSet<ShoppingCartLine>();
这是我尝试使用以下代码创建JPA查询的代码:
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Tuple> cq = cb.createTupleQuery();
Root<ShoppingCart> carts = cq.from( ShoppingCart.class );
Join<ShoppingCart, ShoppingCartLine> lines = carts.join( "shoppingCartLines", JoinType.LEFT);
cq.multiselect( carts.<Long>get( "id" ), cb.count( lines ));
cq.groupBy( carts.<Long>get("id") );
Query tq = em.createQuery( cq );
return tq.getResultList();
运行此命令时,我得到一个SQLGrammerException,对我来说生成的SQL看起来不正确。
select
shoppingca0_.id as col_0_0_,
count(.) as col_1_0_
from
SHOPPINGCART shoppingca0_
left outer join
SHOPPINGCARTLINE shoppingca1_
on shoppingca0_.id=shoppingca1_.shoppingCart_id,
SHOPPINGCARTLINE shoppingca2_
where
shoppingca0_.id=shoppingca2_.shoppingCart_id
group by
shoppingca0_.id
我应该提到我正在将Hibernate 3.5.4与MySQL5Dialect一起使用
这是我要生成的查询:
select
sc.id,
count(scl.id)
from
shoppingcart sc
left join
shoppingcartline scl
on
scl.shoppingCart_id = sc.id
group by
sc.id
知道我在做什么错吗? 谢谢。
尝试将连接和多选行替换为
SetJoin<ShoppingCart, ShoppingCartLine> lines =
carts.joinSet( "shoppingCartLines", JoinType.LEFT);
cq.multiselect( carts.<Long>get( "id" ), cb.count( lines.<Long>get( "id" ) ));
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