public function all( $as = null ) {
		$this->all_columns = true;

		if ( $as ) {
			$this->all_as = $as;
		}

		return $this;
	}
public function all( $as = null ) {
		$this->all_columns = true;

		if ( $as ) {
			$this->all_as = $as;
		}

		return $this;
	}
public function all ( $ as = null ) { $ this -> all_columns = true ; if ( $ as ) { $ this -> all_as = $ as ; } return $ this ; }
Convert this select statement to retrieve all columns.

@since 2.0

@param string $as

@return $this
Convert this select statement to retrieve all columns .