在同一个查询选择不同的过滤器聚集

Question

这里是我的查询

SELECT 
    client_id, 
    TimesTested, 
    CAST(COUNT(*) AS varchar(30)) AS count, 
    CAST(AVG(testfreq) as varchar(30)) as TestFreq, 
    CAST(STDEV(TestFreq) as varchar(30)) Stdv 
    FROM counted 
    GROUP BY 
    client_id, 
    TimesTested 

它的工作原理;然而，我需要筛选AVG和STDEV，其中testfreq> 0，但我需要计数（*）不被过滤。

最接近的事是：

SELECT 
    client_id, 
    TimesTested, 
    CAST(COUNT(*) AS varchar(30)) AS count, 
    CAST(AVG(testfreq) as varchar(30)) as TestFreq, 
    CAST(STDEV(TestFreq) as varchar(30)) Stdv 
    FROM counted 
    where testfreq>0 --however I don't want this filtered applied to count(*) 
    GROUP BY 
    client_id, 
    TimesTested 

非常感谢您的指导！

Answer 1

您应该能够使用CASE语句进行汇总与此类似：

SELECT client_id, 
    TimesTested, 
    CAST(COUNT(*) AS varchar(30)) AS count, 
    CAST(AVG(case when testfreq>0 then testfreq end) as varchar(30)) as TestFreq, 
    CAST(STDEV(case when testfreq>0 then TestFreq end) as varchar(30)) Stdv 
FROM counted 
GROUP BY client_id, TimesTested 

我不知道为什么你需要这些为VARCHAR处理，有没有你需要这些值转换为varchar理由吗？

我只想离开这个值是：

SELECT client_id, 
    TimesTested, 
    COUNT(*) AS count, 
    AVG(case when testfreq>0 then testfreq end) as TestFreq, 
    STDEV(case when testfreq>0 then TestFreq end) Stdv 
FROM counted 
GROUP BY client_id, TimesTested