如何写这样一条sql

请教高手怎么写这样一条sql
date_id biz_tag
2011-08-22 tag1
2011-08-22 tag2
2011-08-22 tag3

转成
date_id biz_tag1 biz_tag2 biz_tag3
2011-08-22 tag1 tag2 tag3

[解决办法]

SQL code

with t as(    select '2011-08-22' as date_id, 'tag1' as biz_tag from dual     union all    select '2011-08-22' as date_id, 'tag2' as biz_tag from dual     union all    select '2011-08-22' as date_id, 'tag3' as biz_tag from dual)select tab1.date_id,       replace(wmsys.wm_concat(case when tab1.biz_tag = 'tag1' then tab1.biz_tag else '' end), ',' , '') as biz_tag1,       replace(wmsys.wm_concat(case when tab1.biz_tag = 'tag2' then tab1.biz_tag else '' end), ',' , '') as biz_tag2,       replace(wmsys.wm_concat(case when tab1.biz_tag = 'tag3' then tab1.biz_tag else '' end), ',' , '') as biz_tag3  from (select date_id, biz_tag from t group by date_id, biz_tag) tab1 group by tab1.date_id;DATE_ID    BIZ_TAG1  BIZ_TAG2  BIZ_TAG3---------- --------- --------- --------2011-08-22 tag1      tag2      tag3
[解决办法]
SQL code
----date_id biz_tag1 biz_tag2 biz_tag32011-08-22 tag1 tag2 tag3select date_id,sum(decode(biz_tag,tag1,null)) biz_tag1 ,sum(decode(biz_tag,tag2,null)) biz_tag2,sum(decode(biz_tag,tag3,null)) biz_tag3from tbgroup by date_id
[解决办法]
3楼写的复杂了啊
SQL code
with t as(    select '2011-08-22' as date_id, 'tag1' as biz_tag from dual     union all    select '2011-08-22' as date_id, 'tag2' as biz_tag from dual     union all    select '2011-08-22' as date_id, 'tag3' as biz_tag from dual)SELECT date_id,MAX(decode(biz_tag,'tag1','tag1','')) biz_tag1,MAX(decode(biz_tag,'tag2','tag2','')) biz_tag2,MAX(decode(biz_tag,'tag3','tag3','')) biz_tag3 FROM tGROUP BY date_id