HQL右外连接

Question

我试图在HQL中执行正确的外连接.查询创建如下所述:

Query query = this.sessionFactory
            .getCurrentSession()
            .createQuery(
"select 
       O.customer.id as id, 
       O.customer.firstName as firstName, 
       O.customer.lastName as lastName, 
       O.customer.address as address, 
       O.customer.city as city, 
       count(O.id) as totalOrders 
 from 
       Order O 
       right outer join O.customer 
 group by 
       O.customer.id");

mysql上的SQL查询工作正常,但HQL查询返回内连接的结果.

SQL查询是:

select c.id,
    c.firstname,
    c.lastname,
    c.city,
    count(o.id) as total_order
  from orders o right outer join customers c
  on c.id = o.customer_id group by id

Answer 1

问题在于您编写查询的方式.因为您使用O.customer.XXXX,所以Hibernate会在Order和Customer之间添加一个内部联接,以便解析O.customer.您需要重新编写查询以通过在右内连接中引入O.customer的别名来使用右内连接的结果.

select C.id as id, C.firstName as firstName, C.lastName as lastName, 
  C.address as address, C.city as city, count(O.id) as totalOrders 
from Order O right outer join O.customer C 
group by C.id

如果你看一下,Hibernate对您的查询生成的SQL,你会看到,它正在执行两个内部连接和订单和客户之间的右内连接.