Question

我有一张桌子如下

Code   ActionType      user  Date
ABC      1             john  2012-09-09
BCD      2             john  2012-09-09
BCD      2             john  2012-10-09

我想得到基于用户的代码，我们可以在这里得到user ='john'，并且从这里根据john的代码我将获得代码我应该得到总共1次出现和总共2次出现在一个单独的列和最近日期为2的单独列。我的deisred输出如下所示

Code NumberOf1s     Number of 2s  RECENTDateof1s     RECENTDate of2s
BCD   0              1            NULL                2012-10-09

这是已尝试的代码

select code,ActionType,Count(*) as NumbOf1s from Table Where user='john' and               _ActionType in(1,2) 
GROUP BY ActionType,code

请帮助感谢

Answer 1

使用CASE WHEN仅考虑聚合中的某些属性：

select 
  code,
  count(case when actiontype = 1 then 1 end) as numberof1s,
  count(case when actiontype = 2 then 1 end) as numberof2s,
  max(case when actiontype = 1 then thedate end) as recentdateof1s,
  max(case when actiontype = 2 then thedate end) as recentdateof2s
from mytable
where user = 'john'
and actiontype in (1,2)
group by code
order by code;

and actiontype in (1,2)在这里是可选的，但可以加快查询速度。

CUSTOM GROUP BY

1 个答案: