T- SQL Выберите даты с воскресенья по субботу (с интервалом 2 недели) из таблицы дат за последние n месяцев

Question

Я пытаюсь выбрать указанные c диапазоны дат из таблицы дат и назначить номер недели (2 недели = 1 неделя). Скажем, у меня есть следующая таблица:

Date    WeekOfYear  WeekDayName
12/26/2019  52  Thursday
12/27/2019  52  Friday
12/28/2019  52  Saturday
12/29/2019  53  Sunday
12/30/2019  53  Monday
12/31/2019  53  Tuesday
1/1/2020    1   Wednesday
1/2/2020    1   Thursday
1/3/2020    1   Friday
1/4/2020    1   Saturday
1/5/2020    2   Sunday
1/6/2020    2   Monday
1/7/2020    2   Tuesday
1/8/2020    2   Wednesday
1/9/2020    2   Thursday
1/10/2020   2   Friday
1/11/2020   2   Saturday
1/12/2020   3   Sunday
1/13/2020   3   Monday
1/14/2020   3   Tuesday
1/15/2020   3   Wednesday
1/16/2020   3   Thursday
1/17/2020   3   Friday
1/18/2020   3   Saturday
1/19/2020   4   Sunday
1/20/2020   4   Monday
1/21/2020   4   Tuesday
1/22/2020   4   Wednesday
1/23/2020   4   Thursday
1/24/2020   4   Friday
1/25/2020   4   Saturday
1/26/2020   5   Sunday
1/27/2020   5   Monday
1/28/2020   5   Tuesday
1/29/2020   5   Wednesday
1/30/2020   5   Thursday
1/31/2020   5   Friday
2/1/2020    5   Saturday
2/2/2020    6   Sunday
2/3/2020    6   Monday
2/4/2020    6   Tuesday
2/5/2020    6   Wednesday
2/6/2020    6   Thursday
2/7/2020    6   Friday
2/8/2020    6   Saturday
2/9/2020    7   Sunday
2/10/2020   7   Monday
2/11/2020   7   Tuesday
2/12/2020   7   Wednesday
2/13/2020   7   Thursday
2/14/2020   7   Friday
2/15/2020   7   Saturday
2/16/2020   8   Sunday
2/17/2020   8   Monday
2/18/2020   8   Tuesday
2/19/2020   8   Wednesday
2/20/2020   8   Thursday
2/21/2020   8   Friday
2/22/2020   8   Saturday
2/23/2020   9   Sunday
2/24/2020   9   Monday
2/25/2020   9   Tuesday
2/26/2020   9   Wednesday
2/27/2020   9   Thursday
2/28/2020   9   Friday
2/29/2020   9   Saturday
3/1/2020    10  Sunday
3/2/2020    10  Monday
3/3/2020    10  Tuesday
3/4/2020    10  Wednesday
3/5/2020    10  Thursday
3/6/2020    10  Friday
3/7/2020    10  Saturday
3/8/2020    11  Sunday
3/9/2020    11  Monday
3/10/2020   11  Tuesday
3/11/2020   11  Wednesday
3/12/2020   11  Thursday
3/13/2020   11  Friday
3/14/2020   11  Saturday
3/15/2020   12  Sunday
3/16/2020   12  Monday
3/17/2020   12  Tuesday
3/18/2020   12  Wednesday
3/19/2020   12  Thursday
3/20/2020   12  Friday
3/21/2020   12  Saturday
3/22/2020   13  Sunday
3/23/2020   13  Monday
3/24/2020   13  Tuesday
3/25/2020   13  Wednesday

Моя конечная цель будет такой:

WeekNum SundayDate  SaturdayDate
1       12/29/2019  1/11/2020
2       1/12/2020   1/25/2020
3       1/26/2020   2/8/2020
4       2/9/2020    2/22/2020
5       2/23/2020   3/7/2020
6       3/8/2020    3/21/2020

Если бы я делал это в течение нескольких лет, максимальный WeekNum был бы либо 26 или 27 в зависимости от года.

Я попытался выполнить несколько разных запросов, но не могу правильно рассчитать:

with MinDate_cte (Cut, MinDate)
as (select Cut = (((WeekOfYear + 1) % 52) / 2) + 1, MinDate = Date
    from DimDate
    where (datediff(day, Date, dateadd(day, 7 - datepart(weekday, getdate()), getdate())) % 14) = 0
        and Date between dateadd(month, -7, dateadd(day, 7 - datepart(weekday, getdate()), getdate())) -- Sunday 7 months ago
        and dateadd(day, 7 - datepart(weekday, getdate()), getdate()) -- next upcomming Saturday
    )

select Cut = (((WeekOfYear + 1) % 52) / 2) + 1, MaxDate = dateadd(day, 1, Date), MinDate
from DimDate
join MinDate_cte on MinDate_cte.Cut = (((WeekOfYear + 1) % 52) / 2) + 1
where (datediff(day, Date, dateadd(day, 7 - datepart(weekday, getdate()), getdate())) % 14) = 0
and Date between dateadd(month, -7, dateadd(day, 7 - datepart(weekday, getdate()), getdate())) -- Sunday 7 months ago
                           and dateadd(day, 7 - datepart(weekday, getdate()), getdate()) -- next upcomming Saturday
and dateadd(day, 1, Date) > MinDate
order by Date

Answer 1

Я бы использовал намного проще SQL и просто работал бы по воскресеньям. Это не проверено, так как я только что набрал это здесь, но оно должно быть правильным или близким.

--this is your date range
declare @startdate date = '20191229'
    ,@enddate date = '20200331'

select WeekNum = row_number() over (order by [Sunday]),*
from (
     select date as [Sunday]
        , dateadd(day,14,date) as [Saturday]
        , rn = row_number() over (order by date)
     from [your table]
     where WeekDayName = 'Sunday' 
         and date between @startdate and @enddate) a
where rn % 2 = 1