Generation of any SQL command to the database (From entities or migration versions) does not quote all the reserved keywords (For example a fieldname `right`.

Simple fix that always works: double-quote dbname, schemaname and fieldname

e.g "dbsecurity"."userschema"."users" or "tblusers"

MySQL : use the ` sign.

e.g `security`.`users` or `tblusers` (No support for schemas since I last checked some time ago)

For example:

$queryBuilder
    ->select('DISTINCT c.id')
    ->from('Campaigns', 'c')
    ->leftJoin('c', 'CampaignOperations', 'od', 'od.campaignId = c.id AND od.operation = :operation')
    ->from('BannerGroups', 'bg')
    ->innerJoin('bg', 'BannerGroupStrategies', 'bgs', 'bgs.groupId = bg.id AND bgs.advSystem = :system')
    ->where('bg.campaignId = c.id');

Builded the query:

SELECT DISTINCT c.id FROM Campaigns s 
  LEFT JOIN CampaignOperations od ON (od.campaignId = c.id AND od.operation = :operation)
  INNER JOIN BannerGroupStrategies bgs ON (bgs.groupId = bg.id AND bgs.advSystem = :system), 
  BannerGroups bg
  WHERE (bg.campaignId = c.id)

If this query execute on mysql, we get error:
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'bg.id' in 'on clause'

Expected result:

SELECT DISTINCT c.id FROM Campaigns s 
  LEFT JOIN CampaignOperations od ON (od.campaignId = c.id AND od.operation = :operation),
  BannerGroups bg
  INNER JOIN BannerGroupStrategies bgs ON (bgs.groupId = bg.id AND bgs.advSystem = :system)
  WHERE (bg.campaignId = c.id)

Regression after patch https://github.com/doctrine/dbal/pull/175

When trying to use the mysql assignment operator in a native query one gets an exception as SqlParserUtils does not qualify the character after the : as being part of a valid parameter value.

Undefined index: in vendor/doctrine/dbal/lib/Doctrine/DBAL/SQLParserUtils.php line 156 (uncaught exception)

A simple example is
$rsm = new ResultSetMapping();
$rsm->addScalarResult('rank', 'rank');
$qry = $em->createNativeQuery("
SELECT (@rank := 1) AS rank
");
$result = $qry->getResult(Query::HYDRATE_ARRAY);

Or a more complicated example is (similar to actual use):

$rsm = new ResultSetMapping();
$rsm->addScalarResult('rank', 'rank');
$qry = $em->createNativeQuery("
SELECT rank FROM
(SELECT (@rank := @rank +1) AS rank FROM (SELECT @rank :=0) rnk2) rnk1
");
$result = $qry->getResult(Query::HYDRATE_ARRAY);

I have attached quick-fix patch, but it looks like the getPlaceholderPositions method is wanting something better overall (due to the TODO comment in it).