hibernate - 不为空的条件子查询

Question

我想将以下子查询转换为使用休眠子查询：

getCurrentSession().createQuery("from Employee where id in (select adminId from Department where adminId is not null)")
                   .list();

• 员工：

  @ManyToOne
  @JoinColumn(name = "fk_department_id", nullable = true) 
  private Department department;
  

• 部门：

  @OneToMany(fetch = FetchType.EAGER)
  @JoinColumn(name = "fk_department_id")
  private Set<Employee> employees = new HashSet<Employee>(0);
  

谁能给我一个这个转换的例子，因为我读了一些例子，但我仍然不知道如何做到这一点。

Answer 1

Criteria c = session.createCriteria(Employee.class, "e");
DetachedCriteria dc = DetachedCriteria.forClass(Departemt.class, "d");
dc.add(Restrictions.isNotNull("d.adminId");
dc.setProjection(Projections.property("d.adminId"));
c.add(Subqueries.propertyIn("e.id", dc));

该setProjection调用使子查询adminId仅返回属性而不是整个Department实体。Subqueries.propertyIn创建一个限制：被搜索员工的属性必须id是in子查询返回的结果集。