protected function translateOrderBy() { // @codingStandardsIgnoreLine
		$build = array();

		foreach ( $this->statements['orders'] as $column => $direction ) {

			// in case a raw value is given we had to
			// put the column / raw value an direction inside another
			// array because we cannot make objects to array keys.
			if ( is_array( $direction ) ) {
				list( $column, $direction ) = $direction;
			}

			if ( ! is_null( $direction ) ) {
				$column .= ' ' . $direction;
			}

			$build[] = $column;
		}
		return 'order by ' . join( ', ', $build );
	}