sum over partition by 的用法
2017-03-29 09:49
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原地址
http://blog.csdn.net/wawmg/article/details/40840093
--用法详解
0、select * from wmg_test; ---测试数据
1、select v1,v2,sum(v2) over(order by v2) as sum --按照 v2排序,累计n+n-1+....+1
from wmg_test;
2、select v1,v2,sum(v2) over(partition by v1 order by v2) as sum --先分组,组内在进行 1 中的操作
from wmg_test;
3、select v1,v2,sum(v2) over(partition by v1 order by v1) as sum ---稳定排序
from wmg_test;
4、select v1,v2,sum(v2) over(partition by v1) as sum --相同key的进行回填处理
from wmg_test;
5、select distinct v1,sum_01 --取一条
from (
select v1,sum(v2) over(partition by v1) as sum_01
from wmg_test
) a;
6、当然也可以逆序累加,只需order by desc 即可
总结区别:group by 和partition by的区别
group 单纯分组
partition 也能分组,但还具备累计的功能
http://blog.csdn.net/wawmg/article/details/40840093
--用法详解
0、select * from wmg_test; ---测试数据
1、select v1,v2,sum(v2) over(order by v2) as sum --按照 v2排序,累计n+n-1+....+1
from wmg_test;
2、select v1,v2,sum(v2) over(partition by v1 order by v2) as sum --先分组,组内在进行 1 中的操作
from wmg_test;
3、select v1,v2,sum(v2) over(partition by v1 order by v1) as sum ---稳定排序
from wmg_test;
4、select v1,v2,sum(v2) over(partition by v1) as sum --相同key的进行回填处理
from wmg_test;
5、select distinct v1,sum_01 --取一条
from (
select v1,sum(v2) over(partition by v1) as sum_01
from wmg_test
) a;
6、当然也可以逆序累加,只需order by desc 即可
总结区别:group by 和partition by的区别
group 单纯分组
partition 也能分组,但还具备累计的功能
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