Oracle 列转行函数 Listagg()

原文：http://dacoolbaby.iteye.com/blog/1698957

这是一个Oracle的列转行函数：LISTAGG()

先看示例代码：

1. withtempas(
2. select'China'nation,'Guangzhou'cityfromdualunionall
3. select'China'nation,'Shanghai'cityfromdualunionall
4. select'China'nation,'Beijing'cityfromdualunionall
5. select'USA'nation,'NewYork'cityfromdualunionall
6. select'USA'nation,'Bostom'cityfromdualunionall
7. select'Japan'nation,'Tokyo'cityfromdual
8. )
9. selectnation,listagg(city,',')withinGROUP(orderbycity)
10. fromtemp
11. groupbynation

这是最基础的用法：

LISTAGG(XXX,XXX) WITHIN GROUP( ORDER BY XXX)

用法就像聚合函数一样，通过Group by语句，把每个Group的一个字段，拼接起来。

非常方便。

同样是聚合函数，还有一个高级用法：

就是over(partition by XXX)

也就是说，在你不实用Group by语句时候，也可以使用LISTAGG函数：

1. withtempas(
2. select500population,'China'nation,'Guangzhou'cityfromdualunionall
3. select1500population,'Shanghai'cityfromdualunionall
4. select500population,'Beijing'cityfromdualunionall
5. select1000population,'USA'nation,'NewYork'cityfromdualunionall
6. select500population,'Bostom'cityfromdualunionall
7. select500population,'Japan'nation,'Tokyo'cityfromdual
8. )
9. selectpopulation,
10. nation,
11. city,
12. listagg(city,')withinGROUP(orderbycity)over(partitionbynation)rank
13. fromtemp

总结：LISTAGG()把它当作SUM()函数来使用就可以了。

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!