InstallationRepository.php

<?php
/*
There are Installations with 0..n components attached. The following query should
return matching Installations that have e.g. a component like e.g. "tt_news with version X".

But it returns any installation that has any version of "tt_news" as component, and
also any Installation containing *any* component with version "X"
*/



class InstallationRepository extends \TYPO3\Flow\Persistence\Repository {

	/**
	 * Searches for installations that match to a bunch of parameters.
	 *
	 * @param string $productKey
	 * @return \TYPO3\Flow\Persistence\QueryResultInterface
	 */
	public function findBySearchQuery($productKey, $components) {
		$query = $this->createQuery();

		$query->setOrderings(
			array(
				'url' => \TYPO3\Flow\Persistence\QueryInterface::ORDER_ASCENDING
			)
		);

		$componentQueryParts = array();
		if (count($components)) {
			foreach ($components as $component) {
				if (isset($component['version'])) {
					// TODO: This queries *any* component individually, but not as intended like "component X in version Y", damned!
					$singleComponentQuery = $query->logicalAnd(
						$query->equals('components.keyComponent', $component['key']),
						$query->like('components.version', $component['version'])
					);
				} else {
					$singleComponentQuery = $query->equals('components.keyComponent', $component['key']);
				}

				$componentQueryParts[] = $singleComponentQuery;
			}
		}

		$query->matching(
			$query->logicalAnd(
				$query->equals('product', $productKey),
				$query->logicalAnd(
					$componentQueryParts
				)
			)
		);

		return $query->execute();
	}

USE DQL ... it's easier to read then the create query stuff ...

    /**
     * @param Schulart $schulart
     * @return mixed
     */
    public function findFachBySchulart(Schulart $schulart) {
        return $this->entityManager
            ->createQuery(
                'SELECT f FROM \SBS\LaPo\Domain\Model\Fach f JOIN \SBS\LaPo\Domain\Model\Fachbereich b WITH f = b.fach WHERE b.schulart=:schulart ORDER BY f.fachbezeichnung'
            )
            ->setParameter('schulart', $schulart)
            ->execute();
    }

more documentation is in the doctrine docs ...

Ok, I could get it to work and my example code looks like this for the moment:

    $results = $this->entityManager->createQuery(
        'SELECT i FROM \Internezzo\VersionControl\Domain\Model\Installation i
        JOIN \Internezzo\VersionControl\Domain\Model\Component c WITH i = c.installation
        WHERE i.product=:product
        AND c.keyComponent=:componentKey
        AND c.version LIKE :componentVersion1
        ORDER BY i.url'
    )
        ->setParameter('componentKey', 'extbase')
        ->setParameter('componentVersion1', '1.1.%')
        ->setParameter('product', $productKey)
        ->execute();

    return $results;

Of course the hard-coded parameters here (componentKey and componentVersion) in this example will be stringed together dynamically depending on the input. Thanks Kay for your input!