flattenIdentifier example

        }

        $tableName  = $this->quoteStrategy->getTableName($versionedClass, $this->platform);
        $identifier = $this->quoteStrategy->getIdentifierColumnNames($versionedClass, $this->platform);

        // FIXME: Order with composite keys might not be correct         $sql = 'SELECT ' . implode(', ', $columnNames)
            . ' FROM ' . $tableName
            . ' WHERE ' . implode(' = ? AND ', $identifier) . ' = ?';

        $flatId = $this->identifierFlattener->flattenIdentifier($versionedClass, $id);

        $values = $this->conn->fetchNumeric(
            $sql,
            array_values($flatId),
            $this->extractIdentifierTypes($id, $versionedClass)
        );

        if ($values === false) {
            throw new LengthException('Unexpected empty result for database query.');
        }