"how to get a one-dimensional scalar array as a doctrine dql query result?" Code Answer

PHP < 5.5

You can use array_map, and since you only have on item per array, you can elegantly use 'current' as callback, instead of writing a closure.

$result = $em->createQuery("SELECT a.id FROM Auction a")->getScalarResult();
$ids = array_map('current', $result);

See Petr Sobotka's answer below for additional info regarding memory usage.

PHP >= 5.5

As jcbwlkr's answered below, the recommended way it to use array_column.