任意两个时间之间的星期几的次数-横_兩個日期中間星期幾的次數-优快云博客

本文介绍了一个SQL函数f_weekdaycount，用于计算两个指定日期间各星期出现的次数。该函数不受语言设置影响，并能准确计算出包括开始和结束日期在内的每一天是星期几。

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if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_weekdaycount]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_weekdaycount]
GO

/*--计算任意两个时间之间的星期几的次数(横向显示)

    本方法直接判断 @@datefirst 做对应处理
    不受 sp_language 及 set datefirst 的影响

--邹建 2004.08(引用请保留此信息)--*/

/*--调用示例

    select * from f_weekdaycount('2004-9-01','2004-9-02')
--*/
create function f_weekdaycount(
@dt_begin datetime,
@dt_end datetime
)returns table
as
return(
    select 跨周数
        ,周一=case a
            when -1 then case when 1 between b and c then 1 else 0 end
            when 0 then case when b<=1 then 1 else 0 end
                    +case when c>=1 then 1 else 0 end
            else a+case when b<=1 then 1 else 0 end
                +case when c>=1 then 1 else 0 end
            end
        ,周二=case a
            when -1 then case when 2 between b and c then 1 else 0 end
            when 0 then case when b<=2 then 1 else 0 end
                    +case when c>=2 then 1 else 0 end
            else a+case when b<=2 then 1 else 0 end
                +case when c>=2 then 1 else 0 end
            end
        ,周三=case a
            when -1 then case when 3 between b and c then 1 else 0 end
            when 0 then case when b<=3 then 1 else 0 end
                    +case when c>=3 then 1 else 0 end
            else a+case when b<=3 then 1 else 0 end
                +case when c>=3 then 1 else 0 end
            end
        ,周四=case a
            when -1 then case when 4 between b and c then 1 else 0 end
            when 0 then case when b<=4 then 1 else 0 end
                    +case when c>=4 then 1 else 0 end
            else a+case when b<=4 then 1 else 0 end
                +case when c>=4 then 1 else 0 end
            end
        ,周五=case a
            when -1 then case when 5 between b and c then 1 else 0 end
            when 0 then case when b<=5 then 1 else 0 end
                    +case when c>=5 then 1 else 0 end
            else a+case when b<=5 then 1 else 0 end
                +case when c>=5 then 1 else 0 end
            end
        ,周六=case a
            when -1 then case when 6 between b and c then 1 else 0 end
            when 0 then case when b<=6 then 1 else 0 end
                    +case when c>=6 then 1 else 0 end
            else a+case when b<=6 then 1 else 0 end
                +case when c>=6 then 1 else 0 end
            end
        ,周日=case a
            when -1 then case when 0 between b and c then 1 else 0 end
            when 0 then case when b<=0 then 1 else 0 end
                    +case when c>=0 then 1 else 0 end
            else a+case when b<=0 then 1 else 0 end
                +case when c>=0 then 1 else 0 end
            end
    from(
        select 跨周数=case when @dt_begin<@dt_end
                then (datediff(day,@dt_begin,@dt_end)+7)/7
                else (datediff(day,@dt_end,@dt_begin)+7)/7 end
            ,a=case when @dt_begin<@dt_end
                then datediff(week,@dt_begin,@dt_end)-1
                else datediff(week,@dt_end,@dt_begin)-1 end
            ,b=case when @dt_begin<@dt_end
                then (@@datefirst+datepart(weekday,@dt_begin)-1)%7
                else (@@datefirst+datepart(weekday,@dt_end)-1)%7 end
            ,c=case when @dt_begin<@dt_end
                then (@@datefirst+datepart(weekday,@dt_end)-1)%7
                else (@@datefirst+datepart(weekday,@dt_begin)-1)%7 end)a
)
go