public function select( $fields = '' ) {
		if ( empty( $fields ) ) {
			return $this;
		}

		if ( is_string( $fields ) ) {
			$this->statements['select'][] = $fields;
			return $this;
		}

		foreach ( $fields as $key => $field ) {
			if ( is_string( $key ) ) {
				$this->statements['select'][] = "$key as $field";
			} else {
				$this->statements['select'][] = $field;
			}
		}

		return $this;
	}