oracle利用函数实现多行一列数据合并效果

/* Formatted on 2013-1-11 13:23:55 (QP5 v5.185.11230.41888) */
 CREATE OR REPLACE FUNCTION GetGiftsName (rid  in number)//rid 穿的参数
    RETURN VARCHAR2
  AS
     STR   VARCHAR2 (1000);                                           /*返回的数据集*/
  BEGIN
     DECLARE
        v_medCode VARCHAR2 (100);                                 /*存放临时变量的地方*/
  
       CURSOR D_cursor
       IS
         select b.cproname from cc_promotions a left join cc_progifts b on a.ipromosid=b.ipromosid where a.ipromosid=rid and b.bgift='';
    BEGIN
       OPEN D_cursor;
     loop
     fetch D_cursor into v_medCode;
     EXIT WHEN D_cursor%NOTFOUND;
    if length(STR) > 0 THEN
        STR := STR ||','|| v_medCode;
     ELSE
        STR := STR || v_medCode;
     END IF;
     END LOOP;
     close D_cursor;
    end;
     RETURN STR;
 END GetGiftsName;

select GetGiftsName(428) from dual