public static function buildJoinRelationQuery(Relation $relation, $mainSynonym, $joinSynonym) { $query = ""; if ($relation->getCardinality() == Relation::$manyToMany) { $query .= "INNER JOIN " . $relation->getTable() . " {$joinSynonym} "; $query .= "ON {$joinSynonym}." . $relation->getForeignColumn() . " = " . $mainSynonym . ".id "; } return $query; }