如何计算表中列的每个值？

Question

我有这样一张桌子:

UserID     Customer ID status        
1               1          1
1               2          1 
1               3          1
1               4          2
1               5          1
1               6          3
1               7          2
2               8          1
2               9          2 
 ........

我想总结一下这个表,对此:

 UserID           count(status 1)    count(status 2)   count(status 3)
    1                4                2                     1 
    2                1                2                     3
   .........

我怎么能在PL/SQL中做到这一点？

预先感谢

Answer 1

您可以对UserId进行分组并总结不同的状态代码.

就像是:

select
  UserId,
  sum(case status when 1 then 1 else 0 end) as Status1,
  sum(case status when 2 then 1 else 0 end) as Status2,
  sum(case status when 3 then 1 else 0 end) as Status3
from SomeTable
group by UserId
order by UserId

您也可以考虑简单地对UserId和状态进行分组,尽管结果当然不同:

select UserId, status, count(*)
from SomeTable
group by UserId, status
order by UserId, status