在 postgres 的不同列中获取联合的输出答案

【问题标题】：Taking output of union in different column in postgres在 postgres 的不同列中获取联合的输出
【发布时间】：2017-05-11 19:34:48
【问题描述】：

我在一家拨号器公司工作，我们有一个通话记录表，其中有不同的列。

现在我想获取一个可以计算的输出：

已接通的呼出总数

Select count(*) 
from call_history 
where system_disposition = 'CONNECTED' and call_type = 'OUTBOUND'

系统检测到的总 AMD

Select count(*) 
from call_history 
where system_disposition = 'CONNECTED'

AGent 检测到的总 AMD

Select count(*) 
from call_history 
system_disposition='CONNECTED' and call_id in (
    select call_id 
    from udh 
    where disposition_code = 'Answering machine'
)

现在，如果我使用联合命令，所有结果都进入一列，使用交叉连接会给出重复输出，即限制 2 给出每个条目的输出两次。

请帮我做一个查询，它可以告诉我：

出站连接总数 | AMD by SYSTEM | AMD 代理 |泄漏为 (AMD Agent/(Total))

【问题讨论】：

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标签： mysql sql-server postgresql

【解决方案1】：

您可以合并结果并在单个列中选择每个结果，如下所示：

Select sum(r1) as result1, sum(r2) as redult2, sum(r3) as result3 from(
Select count(*) as r1, 0 as r2,0 as r3 from call_history where system_disposition='CONNECTED' and call_type='OUTBOUND'
Union
Select 0 as r1,count(*) as r2, 0 as r3 from call_history where system_disposition='CONNECTED')
Union
Select 0 as r1, 0 as r2,count(*) as r3 from call_history system_disposition='CONNECTED' and call_id in (select call_id from udh where disposition_code='Answering machine')
)

【讨论】：

【解决方案2】：

对于 Postgresql

select *, "AMD by AGent"::numeric/"Total outbound conected" as "Leakage"
from (
    select
        count(call_type = 'OUTBOUND' or null) as "Total outbound conected",
        count(*) as "AMD by SYSTEM",
        count(exists (
            select 1
            from udh
            where
                disposition_code = 'Answering machine' and
                call_id = call_history.call_id
        ) or null) as "AMD by AGent"
    from call_history
    where system_disposition = 'CONNECTED'
) s

在 9.4+ 中有 aggregate filter

【讨论】：