使用分组的一个SQL查询中的多个计数

我想运行一个查询，以获得按年份和月份分组的未结事件和已结事件的计数，下面的查询在没有分组的情况下可以正常工作，但一旦我添加了组，它将无法工作

SELECT (SELECT COUNT(*) AS Opened FROM Incidents) AS Total 
       (SELECT COUNT(*) AS Solved FROM Incidents WHERE (MONTH(Closedate)=MONTH(Opendate))) AS Solved
GROUP BY YEAR(Incidents.Opendate)

尝试：

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可以将单个SELECT语句与大小写表达式一起使用

SELECT YEAR(Incidents.Opendate) AS [Year], 
       MONTH(Incidents.Opendate) AS [Month], 
       COUNT(*) AS Total,
       SUM(CASE WHEN MONTH(Closedate) = MONTH(Opendate) THEN 1 ELSE 0 END) AS Solved
FROM Incidents
GROUP BY YEAR(Incidents.Opendate), MONTH(Incidents.Opendate)

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我已经设法解决了这个问题，下面是问题

select  COUNT(CASE WHEN Month(Closedate)=Month(Opendate) then 1 else null end) AS closed,COUNT(*) AS Opened
from incidents
Group by Year(Opendate), Month(Opendate)
Order by Year(Opendate), Month(Opendate)

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Shree，上面的查询不起作用。我得到了这个错误（Msg 156，级别15，状态1，第3行关键字“as”附近的语法不正确）。您可能可以省略

else null

位。我认为大多数SQL产品都允许这样做，将缺少的

ELSE

子句默认为

ELSE NULL

。然而，这与@Alexander Fedorenko的答案本质上不一样吗？

select  COUNT(CASE WHEN Month(Closedate)=Month(Opendate) then 1 else null end) AS closed,COUNT(*) AS Opened
from incidents
Group by Year(Opendate), Month(Opendate)
Order by Year(Opendate), Month(Opendate)