replace関数コード - lookworld @ 簡単メモ～

--- 
DROP FUNCTION REPLACE(VARCHAR,VARCHAR,VARCHAR);
 
CREATE FUNCTION REPLACE(VARCHAR,VARCHAR,VARCHAR) RETURNS VARCHAR AS '
 
DECLARE
	v_data ALIAS FOR $1;
	v_match ALIAS FOR $2;
	v_replace ALIAS FOR $3;
 
	p int;
	str varchar;
	temp varchar;
 
BEGIN
 
	temp := v_data;
	p := instr(temp,v_match);
	WHILE p > 0 LOOP
		temp := substr(temp,1,p-1) || v_replace || substr(temp, p+length(v_match));
		p := instr(temp, v_match, p + length(v_replace), 1);
  	END LOOP;
	str := temp;
	return str;
END;
' LANGUAGE 'plpgsql';