public function expression( $function, $column, $as ) {
		$this->select->expression( $function, $this->prepare_column( $column ), $as );

		$this->expressions[] = $as;

		return $this;
	}
public function expression( $function, $column, $as ) {
		$this->select->expression( $function, $this->prepare_column( $column ), $as );

		$this->expressions[] = $as;

		return $this;
	}
public function expression ( $ function , $ column , $ as ) { $ this -> select -> expression ( $ function , $ this -> prepare_column ( $ column ) , $ as ) ; $ this -> expressions [ ] = $ as ; return $ this ; }
Select an expression, such as 'COUNT'.

@since 2.0

@param string $function
@param string $column
@param string $as

@return $this
Select an expression such as COUNT .