我的计数 CTE 返回空白，我怎样才能让它返回为 0？

Question

创建 CTE 以计算从今天到当月月底的剩余天数。所以我今天（2021 年 3 月 30 日）的报告不包括明天的 2021 年 3 月 31 日。

   declare @DespatchTo Date = '03-30-2021'

   WITH mycte AS
    (
      SELECT CAST(Convert(date,getdate()) AS DATETIME) DateValue
      UNION ALL
      SELECT  DateValue + 1
      FROM    mycte   
      WHERE   DateValue  < DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, @DespatchTo) + 1, 0)) --03-31-2021
    )
    
    SELECT SUN.Count as SunCount, SAT.Count as SatCount, WK.Count as WeekCount
    FROM 
    (SELECT  count(*) as Count
    FROM    mycte
    WHERE DatePart("w",DateValue) = 1
    group by DatePart("w",DateValue))
    As SUN,
    
    (SELECT  count(*) as Count
    FROM    mycte
    WHERE DatePart("w",DateValue) = 7
    group by DatePart("w",DateValue))
    As SAT,
    
    (SELECT  distinct SUM(COUNT(*)) OVER() AS Count
    FROM    mycte
    WHERE DatePart("w",DateValue) > 1 AND DatePart("w",DateValue) < 7
    group by DatePart("w",DateValue))
    As WK

返回空白/空结果。我怎样才能返回为 0？

Answer 1

这是你需要做的：

;WITH mycte AS (
    SELECT  GETDATE() DateValue
    UNION ALL
    SELECT DateValue + 1
    FROM mycte
    WHERE DateValue < EOMONTH(GETDATE())
)

select
   count(case when datepart(dw, DateValue) = 1 then 1 end) SUN
 , count(case when datepart(dw, DateValue) = 7 then 1 end) SAT
 , count(case when datepart(dw, DateValue) between 2 and 6 then 1 end) WK
from mycte

如果要排除今天，可以调整 cte ：

;WITH mycte AS (
    SELECT  GETDATE() + 1 DateValue
    WHERE GETDATE() <> EOMONTH(GETDATE())
    UNION ALL
    SELECT DateValue + 1
    FROM mycte
    WHERE DateValue < EOMONTH(GETDATE())
)

select
   count(case when datepart(dw, DateValue) = 1 then 1 end) SUN
 , count(case when datepart(dw, DateValue) = 7 then 1 end) SAT
 , count(case when datepart(dw, DateValue) between 2 and 6 then 1 end) WK
from mycte