Folgenden Code in der jeweiligen Repository-Methode vor "return $query->execute();" einfügen:

TYPO3 6.1

$parser = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Extbase\\Persistence\\Generic\\Storage\\Typo3DbBackend');  
$params = array();  
$queryParts = $parser->parseQuery($query, $params); \TYPO3\CMS\Core\Utility\DebugUtility::debug($queryParts, 'Query');  

TYPO3 6.2

$parser = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Extbase\\Persistence\\Generic\\Storage\\Typo3DbQueryParser');  
$queryParts = $parser->parseQuery($query); \TYPO3\CMS\Core\Utility\DebugUtility::debug($queryParts, 'Query');

TYPO3 8.7

$queryParser = $this->objectManager->get(\TYPO3\CMS\Extbase\Persistence\Generic\Storage\Typo3DbQueryParser::class); \TYPO3\CMS\Extbase\Utility\DebuggerUtility::var_dump($queryParser->convertQueryToDoctrineQueryBuilder($query)->getSQL()); \TYPO3\CMS\Extbase\Utility\DebuggerUtility::var_dump($queryParser->convertQueryToDoctrineQueryBuilder($query)->getParameters());