确定性标量函数，用于获取日期的一年中的一周

Question

这是获取星期几日期的好方法，Deterministic scalar function to get day of week for a date。

现在，谁能帮我创建一个确定性的标量函数来获取一年中的一周作为日期吗？谢谢。

Answer 1

这是确定性的，我可以将其用作计算列。

datediff(week, dateadd(year, datediff(year, 0, @DateValue), 0), @DateValue) + 1 

测试代码：

;
with 
Dates(DateValue) as 
(
    select cast('2000-01-01' as date)
    union all 
    select dateadd(day, 1, DateValue) from Dates where DateValue < '2050-01-01'
)
select 
    year(DateValue) * 10000 + month(DateValue) * 100 + day(DateValue) as DateKey, DateValue,        
    datediff(day, dateadd(week, datediff(week, 0, DateValue), 0), DateValue) + 2 as DayOfWeek,
    datediff(week, dateadd(month, datediff(month, 0, DateValue), 0), DateValue) + 1 as WeekOfMonth,
    datediff(week, dateadd(year, datediff(year, 0, DateValue), 0), DateValue) + 1 as WeekOfYear
    from Dates option (maxrecursion 0)