ORACLE数据库在处理数据过程中经常会碰到多行合并一行的情况，此情况在处理时曾经利用过下面三种处理方式：

方式一：在数据库中自定义函数，通过循环遍历将取到的值合并后输出。

示例：【取化学元素百分比】

CREATE OR REPLACE FUNCTION F_YRLHT_CFMC_20120824(HTH VARCHAR(20))
 LANGUAGE SQL RETURNS VARCHAR(200)
BEGIN
DECLARE STR_1 VARCHAR(200);
DECLARE STR_COL VARCHAR(200) DEFAULT '';
DECLARE  AT_END  INT  DEFAULT  0;
 DECLARE NOT_FOUND CONDITION FOR SQLSTATE '02000';
DECLARE CONNECT_COL CURSOR WITH RETURN FOR
 SELECT (CASE
         WHEN HXYS IS NULL THEN
          ' '
         ELSE
          HXYS
       END) HXYS
  FROM (SELECT DISTINCT RPAD(TARGETNAME, 10, ' ') HXYS, B.ITEMNO
          FROM TBMPV039 B, TBMPV031 A, TBMPV030 C
          LEFT JOIN TBGP22 F ON C.VENDORNO = F.ID
          LEFT JOIN TBGP10 G ON G.ID = C.VENDORNO,
         (SELECT *
                                   FROM TBMPV002
                                  WHERE TABLEID = 'PRINT_COMMON'
                                    AND TWOCOL = 'COMPNAME'
                                    AND ONECOL = 'BX') D,
         (SELECT *
                                   FROM TBMPV002
                                  WHERE TABLEID = 'ADDRESS') E
         WHERE B.PONO = A.PONO
           AND A.COMPID=B.COMPID
           AND A.PONO = C.PONO
           AND A.COMPID=C.COMPID
           AND A.PURTYPE = '02'
           AND A.PONO = HTH)
 ORDER BY ITEMNO;
 DECLARE  CONTINUE  HANDLER  FOR  NOT_FOUND 
         SET  AT_END  =  1;
 OPEN CONNECT_COL;
     INS_LOOP: 
     LOOP 
 FETCH CONNECT_COL INTO STR_1 ;
 IF AT_END=0 THEN
 SET STR_COL=STR_COL||(CASE WHEN STR_1 IS NULL THEN '            ' ELSE LPAD(STR_1,12,' ') END);
 END IF;
  IF  AT_END  <>0    THEN   
             LEAVE  INS_LOOP; 
         END  IF;
END LOOP;
 RETURN STR_COL;
END

方式二：利用SYS_CONNECT_BY_PATH函数。

首先构建树：
-----------------------------------------------
SELECT ZDRDM, DJH, RN, LEAD(RN) OVER(PARTITION BY ZDRDM ORDER BY RN) RN1
  FROM (SELECT ZDRDM, DJH, ROW_NUMBER() OVER(ORDER BY ZDRDM, DJH DESC) RN
          FROM SG_CG_RKD)
--------------------------------------------------
下面以SG采购入库单表为例：
SELECT ZDRDM, MAX(SYS_CONNECT_BY_PATH(DJH, '--')) RESULT
  FROM (SELECT ZDRDM,
               DJH,
               RN,
               LEAD(RN) OVER(PARTITION BY ZDRDM ORDER BY RN) RN1
          FROM (SELECT ZDRDM,
                       DJH,
                       ROW_NUMBER() OVER(ORDER BY ZDRDM, DJH DESC) RN
                  FROM SG_CG_RKD
                 WHERE ZDRDM = '18972'
                   AND GYSID = '902'
                   AND ROWNUM < 6))
 START WITH RN1 IS NULL
CONNECT BY RN1 = PRIOR RN
 GROUP BY ZDRDM;

方式三：利用WM_CONCAT函数。示例如下：