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sql 面试有关问题

热度:24   发布时间:2016-04-24 08:28:08.0
sql 面试问题?
表15
 a1 a2 
 1 a 
 1 b 
 2 x 
 2 y 
 2 z 
用select能显示成以下结果吗? 
1 ab 
2 xyz

------解决方案--------------------
ORACLE10G

SQL code
CREATE TABLE a(a1 INT, a2 VARCHAR2(1));INSERT INTO a VALUES(1,'a');INSERT INTO a VALUES(1,'b');INSERT INTO a VALUES(2,'x');INSERT INTO a VALUES(2,'y');INSERT INTO a VALUES(2,'z');select a1, replace(wmsys.wm_concat(a2),',','') a2 from a group by a1
------解决方案--------------------
SQL code
with tb(a1,a2) as (select 1,'a' from dualunionselect 1,'b' from dualunionselect 2,'x' from dualunionselect 2,'y' from dualunionselect 2,'z' from dual)select a1,replace(wm_concat(a2),',') as ass from tb group by a1/        A1 ASS---------- ----------         1 ab         2 xzySQL>
------解决方案--------------------
列转行问题
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