WITH A AS (SELECT '香港,张家港,北京,上海' A FROM DUAL)
SELECT DECODE(B,0,SUBSTR(A,C),SUBSTR(A,C,B-C)) city  FROM
(
SELECT A,B,(LAG(B,1,0) OVER(ORDER BY LV))+1 C
FROM(
SELECT A,INSTR(A,',',1,LEVEL) B,LEVEL LV FROM A
CONNECT BY LEVEL <=(LENGTH(A) - LENGTH(REPLACE(A,',','')))+1
)
)

香港
张家港
北京
上海

例：select * from table where field in (
WITH A AS (SELECT (select field from table2) A FROM DUAL)
SELECT DECODE(B,0,SUBSTR(A,C),SUBSTR(A,C,B-C)) city  FROM
(SELECT A,B,(LAG(B,1,0) OVER(ORDER BY LV))+1 C
FROM(SELECT A,INSTR(A,',',1,LEVEL) B,LEVEL LV FROM A
CONNECT BY LEVEL <=(LENGTH(A) - LENGTH(REPLACE(A,',','')))+1
)))

WITH temp AS(SELECT '香港,张家港,北京,上海,95,aa' textFROM DUAL)
SELECT regexp_substr (text, '[^,]+', 1, rn) cityFROM temp t1,(SELECT     LEVEL rnFROM DUALCONNECT BY LEVEL <=(SELECT   LENGTH (text)- LENGTH (REPLACE (text, ',', ''))+ 1FROM temp)) t2

select answer from fw_answerANSWER-----------------
   A,B,CA,FB,D,ED

 select substr(answer,instr(','||answer|| ',', ',', 1, t2.row_num),instr(','||answer|| ',', ',', 1, t2.row_num+1)-1-instr(','||answer, ',', 1, t2.row_num)) answerfrom fw_answer t1,(select rownum row_num from user_objects where rownum<= 10) t2where nvl(substr(answer,instr(','||answer||',', ',', 1, t2.row_num),instr(','||answer||',', ',', 1, t2.row_num+1)-1-instr(','||answer, ',', 1, t2.row_num)),'-')!='-'order by answer

  ANSWER-----------------
    AABBCDDEF   

  select substr(answer,t2.row_num*2-1,1) answerfrom fw_answer t1,(select rownum row_num from user_objects where rownum<= 10) t2where nvl(substr(answer,t2.row_num*2-1,1),'-')!='-'order by answer 

    表结构： 1  A1  B1  C2  A2  B3  C3  F4  D转换后变成：      1  A,B,C2  A,B3  C,F4  D

SELECT a.id, wm_concat (a.remark) new_result FROM tb_name a group by a.id