Question

我正在尝试在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

如果您要查看从查询中生成的休眠SQL，您会看到它正在执行两者内部联接和订单与客户之间的右内联接。

HQL右外连接

1 个答案: