Cross Join to DQL - php

Question

I'm trying to convert this I think simple mysql query into Doctrine dql, however, Im experience quite a struggle right now...
SELECT (c.prix-aggregates.AVG) AS test
FROM immobilier_ad_blank c
CROSS JOIN (
SELECT AVG(prix) AS AVG
FROM immobilier_ad_blank)
AS aggregates
Purpose of this: creating z-score.
Original implementation coming from this question Calculating Z-Score for each row in MySQL? (simple)
I thought about creating an association within the entity, but I mean its not necessary, its only for stats.
Edit: Btw, I dont wanna use raw SQL, I will extract the "subquery" from another query builder expression using getDQL. Otherwise, I will have to rewrite my dynamic query builder to take in account for rawSQL.
Edit 2:
Tried this
$subQb = $this->_em->createQueryBuilder();
$subQb->addSelect("AVG(subC.prix) as AMEAN")
->from("MomoaIntegrationBundle:sources\Common", "subC");
$subDql = $subQb->getDQL();
$dql = "SELECT c.prix FROM MomoaIntegrationBundle:sources\Common c INNER JOIN ($subDql) AS aggregates";
Raw dql is:
SELECT c.prix FROM MomoaIntegrationBundle:sources\Common c INNER JOIN (SELECT AVG(subC.prix) as AMEAN FROM MomoaIntegrationBundle:sources\Common subC) AS aggregates
Getting this strange error:line 0, col 70 near '(SELECT AVG(subC.prix)': Error: Class '(' is not defined.
Edit 3:
I found kinda of a hawkish way to make it work but doctrine is stubborn with its implementation of entities and such and forgot that STATISTICS do NOT need ENTITIES !
$subQb = $this->_em->createQueryBuilder();
$subQb->addSelect("AVG(subC.prix) as AMEAN")
->from("MomoaIntegrationBundle:sources\Common", "subC");
$sql = "SELECT (c.prix-aggregates.sclr_0) AS test FROM immobilier_ad_blank c CROSS JOIN "
. "({$subQb->getQuery()->getSQL()}) AS aggregates";
$stm = $stm = $this->_em->getConnection()->prepare($sql);
$stm->execute();
$data = $stm->fetchAll();
If you have a better solution, Im all ears ! I actually dislike this solution.

Answer 1

Starting with Doctrine 2.4 it is possible to JOIN without using a defined association, for example:
SELECT u FROM User u JOIN Items i WITH u.age = i.price
This one doesn't make any sense but you get the point. The WITH keyword is absolutely required in this case, otherwise it is a syntax error, but you can just provide a dummy condition, like so:
SELECT u FROM User u JOIN Items i WITH 0 = 0
This essentially results in a cross join. Whether this is a good idea in a given situation is a different question, but I have encountered situations where this was indeed very useful.

Answer 2

For complex queries you might want to consider bypassing DQL and using a native query - especially since you don't need the result in an entity.
$connection = $em->getConnection();
$statement = $connection->prepare("
select c.prix-aggregates, t1.avg
from immobilier_ad_blank
cross join (
select avg(prix) as avg
from immobilier_ad_blank
) t1
");
$statement->execute();
$results = $statement->fetchAll();