这些是我的（缩写）实体：
@Entity
public class User {
@OneToMany(fetch=FetchType.LAZY)
@JoinTable(name="user_items",joinColumns=@JoinColumn(name="user_id"),inverseJoinColumns=@JoinColumn(name="useritem_id"))
private Set<UserItem> items = Sets.newHashSet();
}
@Entity
@Inheritance(strategy=InheritanceType.JOINED)
public class UserItem {
@Id
@Type(type=EntityConstants.TYPE_UUID)
@Column(columnDefinition=EntityConstants.COL_UUID)
private UUID id;
}
@Entity
public class UserItemFurniture extends UserItem {
}
现在我想UserItemFurniture通过它的 UUID 获取 a ，但前提是它存在 a User's items。这是我的尝试：
em
.createQuery(
"SELECT f " +
"FROM UserItemFurniture f " +
"WHERE f.id = :iid " +
"AND f IN (SELECT u.items FROM User u WHERE u.id = :uid) ",
UserItemFurniture.class
)
.setParameter("uid", userId)
.setParameter("iid", itemId)
.getSingleResult();
但它会生成这个无意义的 SQL：
select useritemfu0_.id as id17_, useritemfu0_1_.item as item17_, useritemfu0_.roomNumber as roomNumber18_, useritemfu0_.x as x18_, useritemfu0_.y as y18_
from UserItemFurniture useritemfu0_ inner join UserItem useritemfu0_1_ on useritemfu0_.id=useritemfu0_1_.id
where useritemfu0_.id=? and (useritemfu0_.id in (
select .
from _User user1_, user_items items2_, UserItem useritem3_
where user1_.id=items2_.user_id and items2_.useritem_id=useritem3_.id and user1_.id=?
))
limit ?
（注意子查询SELECT .：）
我可以在不诉诸本机或多个查询的情况下做到这一点吗？请注意，UserItem没有对 的引用User，这是设计使然。