sql - SQL 多个计数，按月分组

Question

我有表：

STATUS  DEFECT   DATE

CLOSED  IP       01.01.2012 
CLOSED  TV       03.03.2012
CLOSED  ADSL     05.05.2012
CLOSED  ADSL     11.01.2012 
CLOSED  TV       15.01.2012
NEW     TV         
NEW     TV

我想按月份对每个特定缺陷的计数进行分组。被认为是 CLOSED 的状态

结果表我想成为：

MONTH     TV  ADSL  IP
January   1   1     1
March     1   0     0
May       0   1     0

我正在使用 db2 数据库，所以显示月份的部分是：

select case month(timestamp_iso(DATE))
        when 1 then 'January'
        when 2 then 'February'
        when 3 then 'March'
        when 4 then 'April'
        when 5 then 'May'
        when 6 then 'Jun'
        when 7 then 'July'
        when 8 then 'August'
        when 9 then 'September' 
        when 10 then 'October'
        when 11 then 'November'
        when 12 then 'December'
    end as Month

from TABLE
where  STATUS='CLOSED'
group by month(timestamp_iso(DATE))
order by month(timestamp_iso(DATE))

所以我只需要添加这部分来计数。谢谢

Answer 1

您可以使用另一种将计数限制为一个类别中的缺陷的 case 语句来计算缺陷类别：

select case month(timestamp_iso(DATE))
        when 1 then 'January'
        when 2 then 'February'
        when 3 then 'March'
        when 4 then 'April'
        when 5 then 'May'
        when 6 then 'Jun'
        when 7 then 'July'
        when 8 then 'August'
        when 9 then 'September' 
        when 10 then 'October'
        when 11 then 'November'
        when 12 then 'December'
    end as Month,
    count (case when defect = 'TV' then 1 end) TV,
    count (case when defect = 'ADSL' then 1 end) ADSL,
    count (case when defect = 'IP' then 1 end) IP
from TABLE
where  STATUS='CLOSED'
group by month(timestamp_iso(DATE))
order by month(timestamp_iso(DATE))