Generate list of dates based on the day and occurrence of the month - sql

Question

I want to generate based on the day of the week and number of the occurrence in the month of a date, a list of dates for each month between two dates. Assuming I have a #StartDate = 2016/04/01 and #EndDate = 2016/09/01, i check that #StartDate is on a first Friday of April, then to #EndDate will create dates for all first Friday of each month:
2016/05/06
2016/06/03
2016/07/01
2016/08/05
In case #StartDate = 2016/04/12 and #EndDate = 2016/09/01, I note that the #StartDate is the second Tuesday of April, then went to get every second Tuesday Tuesday of each month :
2016/05/10
2016/06/14
2016/07/12
2016/08/09
In case#StartDate = 2016/04/28 and #EndDate = 2016/09/01, I note that the #StartDate is on the last Thursday of the month of April:
2016/05/26
2016/06/30
2016/07/28
2016/08/25
In the last case, i need to verify the number of weeks of each month, because exists months only with 4 weeks or with 5 weeks and i want the last occurrence.
What I have done? I found a code that gives me every Monday in the third week of the month, and i adopted a little to get a #StartDate and #EndDate:
;with
filler as (select row_number() over (order by a) a from (select top 100 1 as a from syscolumns) a cross join (select top 100 1 as b from syscolumns) b),
dates as (select dateadd(month, a-1, #StartDate ) date from filler where a <= 1000 and dateadd(month, a-1, #StartDate) < #EndDate),
FirstMonday as (
select dateadd(day, case datepart(weekday,Date) /*this is the case where verify the week day*/
when 1 then 1
when 2 then 0
when 3 then 6
when 4 then 5
when 5 then 4
when 6 then 3
when 7 then 2
end, Date) as Date
,case when datepart(weekday, #StartDate) = 1 then 3 else 2 end as Weeks /*here i verify the number of weeks to sum in the next date*/
from dates
)
select dateadd(week, Weeks, Date) as ThirdMonday
from FirstMonday

Answer 1

So, it is:
set #NumSemana = datepart(day, datediff(day, DATEADD(mm, DATEDIFF(mm,0,#StartDate), 0), #StartDate)/7 * 7)/7 + 1;
WITH AllDays
AS ( SELECT #StartDate AS [Date], DATEPART(month, #StartDate) as validMonth
UNION ALL
SELECT DATEADD(week, 1, [Date]),
iif(DATEPART(month,DATEADD(week, 1, [Date])) < validMonth + #PeriodicityRepeat, validMonth, validMonth + #PeriodicityRepeat)
FROM AllDays
WHERE
DATEPART(month,[Date]) <= DATEPART(month,#EndDate)
and DATEPART(year,[Date]) <= DATEPART(year,#EndDate)
),
rankedDays
AS(
SELECT [Date], validMonth,
row_number() over ( partition by DATEPART( month, [Date]) order by [Date]) ascOrder,
row_number() over ( partition by DATEPART( month, [Date]) order by [Date] desc) descOrder
FROM AllDays
WHERE DATEPART(month, [Date]) = validMonth
)
select [Date]
from rankedDays
where ((ascOrder = #NumSemana and #NumSemana <=4 )
or (descOrder = 1 and #NumSemana = 5)
or [Date] = #StartDate )
and [Date] < #EndDate
OPTION (MAXRECURSION 0)

Answer 2

Query:
DECLARE #StartDate DATE = '2016-04-28',
#EndDate DATE = '2016-09-01'
;WITH dates AS (
SELECT DATEADD(week, -5, #StartDate) as date_
UNION ALL
SELECT DATEADD(week,1,date_)
FROM dates
WHERE DATEADD(week,1,date_) < #enddate
), final AS (
SELECT ROW_NUMBER() OVER (PARTITION BY DATEPART(year,date_), DATEPART(month,date_) ORDER BY date_ ASC) as RN,
date_
FROM dates
), weeks AS (
SELECT *
FROM (VALUES
(1,1),
(2,2),
(3,3),
(4,4),
(4,5),
(5,4),
(5,5)
) as t(w1,w2)
WHERE w1 = (SELECT RN FROM final WHERE date_ = #StartDate)
)
SELECT MAX(date_) as date_
FROM final f
INNER JOIN weeks w ON f.RN = w.w2
WHERE date_ between #StartDate and #EndDate AND date_ != #StartDate
GROUP BY DATEPART(YEAR,date_), DATEPART(MONTH,date_)
ORDER BY MAX(date_) ASC
Outputs:
For #StartDate = 2016/04/01 and #EndDate = 2016/09/01
date_
----------
2016-05-06
2016-06-03
2016-07-01
2016-08-05
(4 row(s) affected)
For #StartDate = 2016/04/12 and #EndDate = 2016/09/01
date_
----------
2016-05-10
2016-06-14
2016-07-12
2016-08-09
(4 row(s) affected)
For #StartDate = 2016/04/28 and #EndDate = 2016/09/01
date_
----------
2016-05-26
2016-06-30
2016-07-28
2016-08-25
(4 row(s) affected)