论坛积分是论坛积分。
问答积分是问答积分。
不一样的。

还有就是积分有用么？
显得自己很牛？

CSDN来的？

create table tab1(a varchar2(16),b varchar2(16));
insert into tab1 values('a','1');
insert into tab1 values('a','2');
insert into tab1 values('a','3');
insert into tab1 values('b','4');
insert into tab1 values('b','5');
commit;

SELECT A, LTRIM(MAX(SYS_CONNECT_BY_PATH(B, ',')), ',') B
  FROM (SELECT A,
               B,
               row_number() over(PARTITION BY A ORDER BY A, B) M,
               (ROW_NUMBER()
                OVER(ORDER BY A, B) + (DENSE_RANK() OVER(ORDER BY A))) NUMID
          FROM (SELECT A, B FROM tab1))
START WITH M = 1
CONNECT BY NUMID - 1 = PRIOR NUMID
GROUP BY A

create table tab1(a varchar2(16),b varchar2(16));
insert into tab1 values('a','1');
insert into tab1 values('a','2');
insert into tab1 values('a','3');
insert into tab1 values('b','4');
insert into tab1 values('b','5');
commit;

SELECT A, LTRIM(MAX(SYS_CONNECT_BY_PATH(B, ',')), ',') B
  FROM (SELECT A,
               B,
               row_number() over(PARTITION BY A ORDER BY A, B) M,
               (ROW_NUMBER()
                OVER(ORDER BY A, B) + (DENSE_RANK() OVER(ORDER BY A))) NUMID
          FROM (SELECT A, B FROM tab1))
START WITH M = 1
CONNECT BY NUMID - 1 = PRIOR NUMID
GROUP BY A

oracle9i上面测试通过。

select t.filed1,wmsys.wm_concat(t.filed2)  from table t group by t.filed1

 oracle 10g 测试用过。

oracle 支持多个分组,但是连接字段小于4000字符
SELECT t.filed1, MAX(substr(sys_connect_by_path(t.filed2, ','), 2)) str
FROM table1 t
START WITH filed2= 1
CONNECT BY filed2= PRIOR filed2+ 1
AND filed1= PRIOR filed1
GROUP BY t.filed1;

select field1,group_concat(field2) as 'all' from table group by field1

google 搜索 行列转换 函数,应该有你想要的结果

WMSYS.WM_CONCAT支持的字符串的最大长度是4000，如果超过4000有什么好办法吗？

oracle数据库sql
方法1：
select (select distinct field1 from tablename) field1,(select  field2||','  from tablename
where  field2='1')||
(select  field2||',' from tablename
where  field2='2')||(select  field2  from tablename
where  field2='3') all
from dual
方法2：
select distinct field1 ,
                MAX(decode(field2, '1',field2 || ',', NULL)) ||
                MAX(decode(field2, '2', field2 || ',', NULL)) ||
                MAX(decode(field2, '3', field2))
  from tablename
  where field1='A'
group by field1

用oracle怎么都得用函数来解决，还不如自己写个函数，wm_sys.concat这个函数返回值是clob型的，长度问题倒是不用考虑。