加入HQL子查询

Question

我有一个类Order包含一组OrderIction本身包含一组OrderItem's。

在SQL中，一个可以在JOIN子句中使用SELECT语句，如下面的查询完成：

SELECT 
    o.id, 
    o.amount, 
    sum(s.quantity*s.price), 
    sum(s.quantity*i.price) 
FROM 
    orders AS o 
    JOIN ordersections AS s ON s.order_id=o.id 
    JOIN (SELECT section_id, sum(quantity*price) AS price FROM orderitems GROUP BY section_id) AS i ON i.section_id=s.id 
GROUP BY o.id, o.amount 

有没有可能来表达HQL这样的查询？

Answer 1

除非我失去了一些东西，你的查询可以在SQL重写为：

SELECT 
    o.id, 
    o.amount, 
    sum(s.quantity*s.price), 
    sum(s.quantity*i.quantity*i.price) 
FROM orders AS o 
    JOIN ordersections AS s ON s.order_id=o.id 
    JOIN orderitems AS i ON i.section_id=s.id 
GROUP BY o.id, o.amount 

在这种情况下，然后可以在HQL改写为：如果我丢失

SELECT 
    o.id, 
    o.amount, 
    sum(s.quantity*s.price), 
    sum(s.quantity*i.quantity*i.price) 
FROM orders AS o 
    JOIN o.sections AS s 
    JOIN s.items AS i 
GROUP BY o.id, o.amount 

有些东西和上面的查询没有返回你想要的，你用HQL转换运气不好，因为Subqueries in HQL can only occur in SELECT or WHERE clauses。但是，您可以将您的查询映射为<sql-query> - 最终应该没有任何区别。