Question

在SQL Server中，这两个日期之间有多少8天的时间段？

@date1 = '2016/11/08'
@date2 = '2017/02/10'

手动我在这些日期之间有四个8天的时间段

Answer 1

Declare @date1 date = '2016/11/08'
Declare @date2 date = '2017/02/10'

Select count(*)
 From (
        Select Top (DateDiff(DD,@date1,@date2)+1) D=cast(DateAdd(DD,Row_Number() Over (Order By (Select null))-1,@date1) as Date) 
        From master..spt_values n1, master..spt_values n2 
      ) A
 Where DatePart(DAY,D)=8

返回

Answer 2

这是使用标准SQL Date函数的替代方法：

 declare @StartDate datetime = '2016-11-08'
, @EndDate datetime = '2023-10-09' --'2017-02-10' 
, @dayOfInterest int = 8 --in case you decided you were interested in a different date

--if you don't care whether or not start date is before or after end date; swap their values...
/*
select @StartDate = min(d)
, @EndDate = max(d)
from (select @StartDate d union select @EndDate) x
*/

select 
case when @StartDate <= @EndDate then
    --if the end date is after or on the start date, we count the number of eighths in between
    datediff(month,@StartDate,@EndDate) --count the number of months between the two dates
    + case when datepart(dd,@StartDate)<=@dayOfInterest then 0 else -1 end --if our range excludes the nth this month, exclude it
    + case when datepart(dd,@EndDate)<@dayOfInterest then 0 else 1 end --if our range includes the nth on the last month, include it
else 
    0 --if the end date is before the start date; we return 0
end
CountTheDays --give the output column a name

<强>注意

注意：对于第8名，这将完美地运作。对于28日之后的日期，这是不可靠的（你最好使用John Cappelletti's solution），因为我的逻辑将每月增加1天，无论那个月是否包含当天（即如果计算当天的数量）在1月1日到3月1日之间的30日，你得到2而不是1，因为我的逻辑假设2月30日是有效的日期。

计算SQL Server两个日期之间一天发生的次数

2 个答案: