java - 如何在HQL中进行除法、计算百分比？

Question

我正在尝试计算百分比，但编译器一直告诉我它不需要斜杠和第三个选择语句。

Query query = session.createQuery("SELECT 
(SELECT COUNT(*) FROM Reservation r WHERE r.begin BETWEEN :start AND :end) 
/
(SELECT COUNT(*) FROM Reservation res WHERE res.begin BETWEEN :start AND :end AND res.contract IS NOT NULL) * 100");

当我尝试运行它时，它给了我这个错误:

Exception in thread "main" org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected end of subtree

我做错了什么？提前致谢!

Answer 1

两个计数可以合并为一个查询:

SELECT (count(r.contract) / count(r)) * 100 
FROM Reservation r 
WHERE r.begin between :start and :end

在某些数据库中，导致整数除法并且以下更好:

SELECT (count(r.contract)*1.0 / count(r)) * 100 
FROM Reservation r 
WHERE r.begin between :start and :end