Join two Entities in a DQL Query

Question

I have two entities with one-to-many relation using annotation in my DQL Query. What is the difference between those two queries?

1-

SELECT p, c FROM AcmeStoreBundle:Product p
    JOIN p.category c
WHERE p.id = :id

2-

SELECT p, c FROM AcmeStoreBundle:Product p
    JOIN AcmeStoreBundle:Category c
        ON p.categoryid = c.id
WHERE p.id = :id

When I check the benchmark I found the second approach take less time. Can someone list the pros and cons for each way and when each one is useful?

Can you please give the result of the benchmark? You can compare the resulting queries by [displaying them](http://stackoverflow.com/a/11379563/2257664). — A.L, Mar 11 '14 at 01:01

score 1 · Accepted Answer · answered Mar 10 '14 at 23:43

According to official documentation you cannot execute the second query. I haven't actually tried it but you say it's possible? If so, I believe, it's bad practice to express relations in such manner...

Every ORM is object oriented, and such emphasizes the need for objects rather than ids. Your second query look more like a native query of relational database where JOIN works with ids.

Join two Entities in a DQL Query

1 Answers1