在SQL查询中同时使用计数和并集

我有两个SQL查询

select count ( distinct w.processno ) AS "Number of Processes", y.userid from upmfolder f, upmperson p, w2process w, w2processcheck y where f.personid = p.personid and f.folderid = w.keynumb and w.Processno = y.processid and w.keyobject ='UPMFolder' group by 2

另一个类似的例子是：

select count ( distinct w.processno ) AS "Number of Processes", y.userid from upmfolder f, upmperson p, w2process w, w2processcheck y where f.personid = p.personid and f.payrollmemberid = w.keynumb and w.keyobject = 'UPMPayrollmember' and w.Processno = y.processid group by 2

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如何将这两个查询组合成一个查询？因此，计数和组仍能正常工作。我尝试了使用

联合所有

，但是没有成功。我需要做什么？

您可以通过条件聚合来完成。对于计数（不同），您需要提供空值：

select y.userid,
       count(distinct case when w.keyobject ='UPMFolder' then w.processno end) as NumFolder, 
       count(distinct case when w.keyobject ='UPMPayrollMember' then w.processno end) as NumPayrollMember
from upmfolder f, upmperson p, w2process w, w2processcheck y
where f.personid = p.personid and
      f.folderid = w.keynumb and
      w.Processno = y.processid
group by y.userid

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注意：您还应该学习现代

join

语法。我没有更改查询，但是连接条件实际上应该在

on

子句中，而不是

where

子句中。

这不取决于您希望作为一个整体计算的内容吗？我的意思是，您希望如何处理满足这两个查询的流程？算一次？两次？我只数了一次