Q:

Sub-Query in Spring Data Jpa

I have query like this in jpql 
select new com.example. CustomGroup(m.id, m.title, (select count(w.id) from MessageGroup x join x.messages w where w.readers.id <> ? 1) ) 
from MessageGroup m join m.members u where u.id = ? 1

but not work, i know jpa 2 support sub query in select but cant find any refrence to how use it 

A:

Quote from the JPA 2.2 specification, paragraph 4.6.16:

Subqueries may be used in the WHERE or HAVING clause.[66]
[66] Subqueries are restricted to the WHERE and HAVING clauses in this release.  Support for subqueries in the FROM clause will be considered in a later release of this specification.