Why does Doctrine QueryBuilder destroy my query?

Question

I am trying to receive the latest id in a table. Therefore I created a static class to be able to fetch this latest id from any desired table.

public static function getLatestId($entityManager, $table, $column) {
    $qb = $entityManager->createQueryBuilder();
    $qb->select('t.'.$column)->from($table, 't')
       ->orderBy('t.'.$column, 'DESC')->setMaxResults(1);
    $query = $qb->getQuery();
    $result = $query->getSingleResult();
    $latestId = $result[$column];
    return $latestId;
}

When I call the function e.g. with getLatestId($em, 'company', 'companyId') and check the query (with getQuery(), it creates weird statement:

SELECT c0_.companyId AS companyId0 FROM company c0_
ORDER BY c0_.companyId DESC LIMIT 1

Why does it replace the t. by c0_. and suffixes a 0 to the column?

Maybe using parameters in the `select` clause is possible, at least it seems like that if looking at [another question](http://stackoverflow.com/questions/13689095/how-can-i-pass-a-parameter-to-a-doctrine2-custom-function-in-the-query-builder-s) at Stack Overflow. But I don't get why it doesn't work in my case. — Gottlieb Notschnabel, Aug 05 '13 at 09:25

score 1 · Accepted Answer · answered Aug 05 '13 at 10:11

First you are retreiving a partial, which will return a scalar variable by default. So for clarity it's good to use the getSingleScalarResult() method. See also: http://docs.doctrine-project.org/en/latest/reference/partial-objects.html

Then you are trying to read the userId column, but you passed the companyId column. So replace this:

$latestId = $result['userId'];

with this:

$latestId = $result[$column];

Don't worry about the aliases Doctrine gives to your columns. This is normal behaviour and it helps Doctrine to map everything the right way internally.

Why does Doctrine QueryBuilder destroy my query?

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