如何找出每周开始日期

Question

我有一个存储功能，它应该弄清楚工资单周我的开始日期。这是“星期四”然而，我的存储过程总是让我的开始日期为“星期五”我的声明和设置功能有什么问题？我希望我的StartWeekDay是“星期四” ...“lStartday”设置为在帐户表“5”我的代码如下：

DECLARE @StartWeekDay int 
SET @StartWeekDay = (Select lStartDay From Account Where lLocationID = 1) 

DECLARE @CurrentDate DateTime 
SET @CurrentDate = GetDate() 
DECLARE @CurrentWeekDay int 
SET @CurrentWeekDay = DATEPART(dw,@CurrentDate) 

DECLARE @Diff int 
SET @Diff = @StartWeekDay - @CurrentWeekDay 

SET @Diff = Case When @Diff > 0 Then -6 When @Diff = 0 Then 0 Else @Diff End 

-- 
DECLARE @DaysToStart int 
SET @DaysToStart = (DatePart(dw,@CurrentDate) - @StartWeekDay) 
IF @DaysToStart <= .1 
    BEGIN 
    SET @DaysToStart = @DaysToStart + 7 
    END 

DECLARE @myStartWeekDate DateTime 
--SET @myStartWeekDate = dbo.DateOnly(DATEADD(d,@Diff,@CurrentDate)) 
SET @myStartWeekDate = Convert(nvarchar,DateAdd(d,-@DaysToStart,@CurrentDate),101) -- getting DATE only 
-- 

Answer 1

lStartDay = 5总会作罢周五。您需要添加4

DECLARE @DaysToStart int 
SET @DaysToStart = (DatePart(dw,@CurrentDate) - @StartWeekDay) 
IF @DaysToStart <= .1 
    BEGIN 
    SET @DaysToStart = @DaysToStart + 7 
    END 

如果您声明@DaysToStart周四和日期部分也返回INT，为什么.1比较？

Answer 2

下面的查询是四舍五入日期的一周beginiing的标准方法。然而，这被视为一个星期一......

DATEADD(WEEK, DATEDIFF(WEEK, 0, @YourDate), 0) 

如果通过3抵消你的价值观，这将改变功能向下舍到上周四...

DATEADD(WEEK, DATEDIFF(WEEK, 0, @YourDate-3), 3) 

编辑：这应该是3，4不...

SET @yourDate = getDate() 
SET @firstDay = 3 
SET @RoundedDate = DATEADD(WEEK, DATEDIFF(WEEK, 0, @YourDate-@firstDay), @firstDay) 

Value of @firstDay | Day of week this will round to 
--------------------+-------------------------------- 
     0   |  Monday 
     1   |  Tuesday 
     2   |  Wednesday 
     3   |  Thursday 
     4   |  Friday 
     5   |  Saturday 
     6   |  Sunday 

Answer 3

 DECLARE @StartWeekDay int 
    SET @StartWeekDay = 5 

    DECLARE @CurrentDate DateTime 
    SET @CurrentDate = '8/24/2012' 
    DECLARE @CurrentWeekDay int 
    SET @CurrentWeekDay = DATEPART(dw,@CurrentDate) 
    SELECT @CurrentWeekDay; 

    DECLARE @Diff int 
    SET @Diff = @StartWeekDay - @CurrentWeekDay 

    SET @Diff = Case When @Diff > 0 Then -6 When @Diff = 0 Then 0 Else @Diff End 

    -- 
    DECLARE @DaysToStart int 
    SET @DaysToStart = (DatePart(dw,@CurrentDate) - @StartWeekDay) 
--change here to <1 and not <=1 that will add 8 and return friday at the end 
    IF @DaysToStart < 1 
     BEGIN 
     SET @DaysToStart = @DaysToStart + 7 
     END 
     SELECT @DaysToStart; 
    DECLARE @myStartWeekDate DateTime 
    --SET @myStartWeekDate = dbo.DateOnly(DATEADD(d,@Diff,@CurrentDate)) 
    SET @myStartWeekDate = Convert(nvarchar,DateAdd(d,-@DaysToStart,@CurrentDate),101) 
    SELECT @myStartWeekDate