Question

I am developing an application with Symfony2 and Doctrine, and have a table called status where I store the location and date books, such as:

ID  | Book        | Date       | Location
------------------------------------------------
1   | Book_1      | 2011-08-29 | Home
2   | Book_1      | 2011-08-30 | Office
3   | Book_1      | 2011-09-02 | Friend's House
4   | Book_2      | 2011-09-02 | Office
5   | Book_2      | 2011-09-04 | Home

The status record with the most recent date represents the current (or last known) location of that book. In the above example, Book_1 is currently in “Friend’s House” and Book_2 is in “Home”.

The following code gets any records that at some point had a location of “Home”:

$em = $this->getEntityManager();
$query = $em->createQuery('SELECT s FROM myBookTestBundle:Status s WHERE s.location=:x')->setParameter('x', 'Home');
$status = $query->getResult();

Instead, I would like to select only those books whose current location matches “Home”. In the above example, that would only be record ID = 5 (Book_2).

Is there any way to do this easily with DQL?

Any help is greatly appreciated.

Thanks,
Ralph

Answer 1

The other question is: “Can Doctrine2’s DQL handle subselects?”.

The query for MySQL would be:

select ID,Book,`Date`,Location 
  from Status a 
  where `Date` = 
    (select max(`Date`) from Status group by Book having Book = a.Book) 
    and Location = 'Home';