（JPQL） - 查询获取最多记录数的用户

Question

Excuse me for anking again about this issue but I need to have a JPA query for this:

select username, count(*)
from Records
group by username
order by count(*) desc
limit 1

I thought about smth like:

select r.username,count(*) from Records r order by r.username desc

and then to call

getResultList().get(0)

but I am allowed to write only:

select r from Records r order by r.username desc

and in this case I do not know how to get what I need. Does anyone have any idea?

Answer 1

The SQL query has a group by, and orders by count. The JPA query doesn't have any group by and orders by user name. So I don't see how they could return the same thing.

The equivalent JPQL query is

select r.username, count(r.id)
from Record r
group by r.username
order by count(r.id) desc

If you call setMaxResults(1) on the Query object, the limit clause will be added to the generated SQL query, making it completely equivalent.