如何在JPQL中通过查询来计算一个组返回的所有组？

Question

If I have a group by query

Select e.field1, e.field2...
from Entity w
group by e.field1, e.field2...

How can I count the number of rows not using NativeQuery? I need to do something like this:

select count(*) from
(Select e.field1, e.field2...
from Entity w
group by e.field1, e.field2...)

Is there any way to do with JPQL?

Answer 1

Derived tables are not supported in JPQL, so, the best way to do it is to run a native SQL query.

After all, there is a very good reason why both JPA and Hibernate offer support for SQL queries , don't you agree?

Answer 2

in oracle you can this hql

Select sum(count(*) - count(*) + 1)
from Entity e
group by e.field1, e.field2...

but dose not work in postgres