在我使用 SQL 服务器的情况下，如何使用周数获取周的开始日期和结束日期？

Question

我已经找到获取周数的方法，但是显示日期的方式不同。

实际上当我检查

日期的周数时

select datepart(wk,'2016-01-02')  //Saturday

output: 1

select datepart(wk,'2016-01-03')  //Sunday

output: 2

但是当我使用周数获取周的开始日期和结束日期时，它显示不同。

DECLARE @weekStart INT
DECLARE @weekEnd INT
DECLARE @Year INT

set @weekStart = 1
set @Year = 2016

DECLARE @WeekStartDate date
DECLARE @WeekEndDate date

SET @WeekStartDate = convert(date,DATEADD (WEEK, @weekStart, DATEADD (YEAR, @Year-1900, 0)) - 4 -
                                                DATEPART(DW, DATEADD (WEEK, @weekStart, DATEADD (YEAR, @Year-1900, 0)) - 4) + 1)
SET @WeekEndDate =convert(date,DATEADD (WEEK, @weekStart+1, DATEADD (YEAR, @Year-1900, 0)) - 4 -
                                                DATEPART(DW, DATEADD (WEEK, @weekStart+1, DATEADD (YEAR, @Year-1900, 0)) - 4) + 1)

select @WeekStartDate,@WeekEndDate


output: 
  StartingDate    EndingDate
  --------------------------
  2016-01-03      2016-01-09

I am expecting output is, if I give week = 1 it should give StartingDate = **2016-01-01 and **EndingDate =2016-01-02

for the week number 2, it should give 2016-01-03 2016-01-09

Answer 1

你必须得到一年中第一天是星期几
如果它不等于 1 那么你必须 set @weekStart = @weekStart -1
和 set @StartingDate = first day in year

Answer 2

您可以获得周的绝对值 start/end，然后针对当年的第一周开始和最后一周结束进行调整。你真的只需要计算开始，因为结束是开始 + 6 天：

create procedure spWeekDates @year int, @week int
as
declare @firstWeekDay int
declare @yearStart datetime, @weekStartDate datetime, @weekEndDate datetime

set datefirst 7 -- change as needed
set @yearStart=cast(@year as char(4))+'0101' -- years always start on 01/01 [citation needed]
set @firstWeekDay=datepart(weekday,@yearStart)

-- absolute start/end dates
set @weekStartDate=dateadd(week,@week-1,@yearStart)-@firstWeekDay+1
set @weekEndDate=dateadd(day,6,@weekStartDate)
-- adjusting for target year
if year(@weekStartDate)<@year set @weekStartDate=@yearStart
if year(@weekEndDate)>@year set @weekEndDate=cast(@year as char(4))+'1231'

select @weekStartDate as WeekStartDate, @weekEndDate as WeekEndDate
go

exec spWeekDates 2016,1
exec spWeekDates 2016,2
exec spWeekDates 2016,53
go

结果：

|       WeekStartDate |         WeekEndDate |
|---------------------|---------------------|
| 2016-01-01 00:00:00 | 2016-01-02 00:00:00 |

|       WeekStartDate |         WeekEndDate |
|---------------------|---------------------|
| 2016-01-03 00:00:00 | 2016-01-09 00:00:00 |

|       WeekStartDate |         WeekEndDate |
|---------------------|---------------------|
| 2016-12-25 00:00:00 | 2016-12-31 00:00:00 |

在我使用 SQL 服务器的情况下，如何使用周数获取周的开始日期和结束日期？

How to get the Starting date and ending date of weeks using week number in my case using SQL Server?

sql

sql-server

date

stored-procedures

week-number

在我使用 SQL 服务器的情况下，如何使用周数获​​取周的开始日期和结束日期？

How to get the Starting date and ending date of weeks using week number in my case using SQL Server?

sql

sql-server

date

stored-procedures

week-number

在我使用 SQL 服务器的情况下，如何使用周数获取周的开始日期和结束日期？