I have 2 dates 01/04/2017 and 30/04/2017. I want all the dates between these 2 dates with 7 days interval.
Expected Output :
01/04/2017
08/04/2017
15/04/2017
22/04/2017
29/04/2017
Please help!!
DECLARE #StartDate DATETIME,
#EndDate DATETIME
SELECT #StartDate = '2017-04-01',
#EndDate = '2017-04-30'
SELECT DATEADD(DAY, number*7, #StartDate)
FROM master.dbo.spt_values
WHERE type='P'
AND #EndDate >= DATEADD(DAY, number*7, #StartDate)
One method would be to use a Calendar table. Then return the results from there using the modulus to get the 7th rows:
WITH Dates AS(
SELECT *,
ROW_NUMBER() OVER (ORDER BY [date]) AS RN
FROM DateTable
WHERE [Date] BETWEEN '20170401' AND '20170430')
SELECT *
FROM Dates
WHERE (RN - 1) % 7 = 0;
I've used this solution, as from your post you imply that you might supply any date range, and that the 1st day may not necessarily be a Monday (or other specific day).
Try this
DECLARE #STRT DATETIME='04/01/2017',#END DATETIME ='04/30/2017'
;WITH CTE
AS
(
SELECT
MyDate = CAST(#STRT AS DATETIME)
UNION ALL
SELECT
MyDate = CAST(MyDate AS DATETIME)+7
FROM CTE
WHERE CAST(MyDate AS DATETIME)+7 < CAST(#END AS DATETIME)
)
SELECT
*
FROM CTE
result
Declare #StartDate DATE=CONVERT(DATE,'01/04/2017',104),#EndDate DATE=CONVERT(DATE,'01/12/2017',104)
Declare #String NVARCHAR(MAX)=''
WHILE (#StartDate<=#EndDate AND DATEDIFF(wk,#StartDate,#EndDate)>=0)
BEGIN
SET #String=#String+CONVERT(NVARCHAR(100),#StartDate)+CHAR(10)+CHAR(13)
SET #StartDate=DATEADD(d,7,#StartDate)
END
PRINT #String
GO
I have a table like this:
id: PK bigint
RatePercent: decimal(4, 4)
DateRange: date
I am trying to populate the table as follows:
RatePercentage with all of them 0.12
Date starting from '01-01-2015' to '12-31-2099'
Unfortunately with my query it won't do that and it keeps saying that
Operand type clash: date is incompatible with int
I haven't assigned an int datatype asides from the id bigint. I'm a bit confused.
Here is my query so far:
DECLARE #Date Date
SET #Date = '01-01-2015'
WHILE #Date <= '12-31-2099'
BEGIN
INSERT INTO [dbo].[IMF_Main_VATHistory] (VATRate, VATDate)
VALUES (0.12, #Date + 1);
END
Try this:
DECLARE #Date Date
SET #Date = '01-01-2015'
WHILE #Date <= '12-31-2099'
BEGIN
INSERT INTO [dbo].[IMF_Main_VATHistory] (VATRate, VATDate)
VALUES (0.12, DATEADD(DAY, 1, #Date));
SET #Date = DATEADD(DAY, 1, #Date);
END
You can't issue a direct addition to a DATE datatype, in SQL Server (for reference, I think you can in Oracle). You have to use functions in order to modify a DATE/DATETIME variable (or column).
Here is an example SQLFiddle.
The problem is in you "#Date + 1" I think - The SQL-Server likes to try and convert to INT :)
Use DATEADD that should work
DECLARE #Date Date
SET #Date = '01-01-2015'
WHILE #Date <= '12-31-2099'
BEGIN
INSERT INTO [dbo].[IMF_Main_VATHistory] (VATRate, VATDate)
VALUES (0.12, #Date);
SET #Date = DATEADD(DAY, 1, #Date);
END
I'll advise against using any loop-based or RBAR solution. You can do this using a set-based approach with the help of a Tally Table.
DECLARE #startDate DATE
DECLARE #endDate DATE
SET #startDate = '20150101'
SET #endDate = '20991231';
WITH E1(N) AS(
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
),
E2(N) AS(SELECT 1 FROM E1 a, E1 b),
E4(N) AS(SELECT 1 FROM E2 a, E2 b),
E8(N) AS(SELECT 1 FROM E4 a, E4 b),
Tally(n) AS(
SELECT TOP(DATEDIFF(DAY, #startDate, #endDate) + 1)
ROW_NUMBER() OVER(ORDER BY (SELECT NULL))
FROM E8
)
INSERT INTO IMF_Main_VATHistory(RatePercent, DateRange)
SELECT
0.02, DATEADD(DAY, N-1, #startDate)
FROM Tally
It's faster compared to using CURSORs or WHILE loops.
I have two specific dates.
lets say from 2014-04-04 To 2015-10-04.
I have a plan that says classes of Blah course will be on mon, wed and Fri.
Now I want to get the dates of each mon, wed and Fri from 2014-04-04 to 2015-10-04.
With a calendar table it is simple:
SELECT t.*
FROM dbo.TableName t
INNER JOIN CalendarTable c
ON t.DateColumn = c.Date
WHERE c.Date between '2014-04-04' AND '2015-10-04'
AND DATEPART(dw, c.Date) IN (1,3,5)
How to generate a calendar table (look for "Calendar table").
The standard reply to this by any seasoned SQL Server veteran, would be to create a calendar table. But all too often this is scoffed. So here's a slow and out-of-the-box method:
DECLARE #startDate DATE = '2014-04-04', #endDate DATE = '2015-10-04';
WITH CTE(N) AS (SELECT 1 FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1))a(N)),
CTE2(N) AS (SELECT 1 FROM CTE x CROSS JOIN CTE y),
CTE3(N) AS (SELECT 1 FROM CTE2 x CROSS JOIN CTE2 y),
CTE4(N) AS (SELECT 1 FROM CTE3 x CROSS JOIN CTE3 y),
CTE5(N) AS (SELECT 1 FROM CTE4 x CROSS JOIN CTE4 y),
CTE6(N) AS (SELECT 0 UNION ALL
SELECT TOP (DATEDIFF(day,#startDate,#endDate))
ROW_NUMBER() OVER(ORDER BY (SELECT NULL))
FROM CTE5),
TALLY(N) AS (SELECT DATEADD(day, N, #startDate)
FROM CTE6
WHERE DATENAME(weekday,DATEADD(day, N, #startDate)) IN ('Monday','Tuesday','Wednesday'))
SELECT N
FROM TALLY
ORDER BY N;
You can use a Recursive CTE if you do not have numbers table. Something like this. Note that the DATEPART(weekday,Dates) IN(1,3,5) is based on your setting of SELECT ##DATEFIRST.
For example If ##DATEFIRST is 1 then use DATEPART(weekday,Dates) IN(1,3,5)
DECLARE #StartDate DATETIME
DECLARE #EndDate DATETIME
SET #StartDate = '2014-04-04'
SET #EndDate = '2015-10-04'
;WITH CTE AS
(
SELECT #StartDate Dates
UNION ALL SELECT DATEADD(d,1,Dates) FROM CTE WHERE DATEADD(d,1,Dates) <=#EndDate
)
SELECT Dates,DATENAME(weekday,Dates) FROM CTE
WHERE DATEPART(weekday,Dates) IN(1,3,5)
OPTION (MAXRECURSION 0);
GO
DECLARE #StartDate DATETIME
DECLARE #EndDate DATETIME
SET #StartDate = '2014-04-04'
SET #EndDate = '2015-10-04'
;WITH CTE AS
(
SELECT #StartDate Dates
UNION ALL SELECT DATEADD(d,1,Dates) FROM CTE WHERE DATEADD(d,1,Dates) <=#EndDate
)
SELECT Dates,DATENAME(weekday,Dates) FROM CTE
WHERE DATEPART(weekday,Dates) IN(1,3,5)
OPTION (MAXRECURSION 0);
GO
--- thanks to #ughai
I've comeup with another way to do this.
this query will not only Show the dates in between but also it will compare the dates u want to compare with.
Q.Dates Comparison
DECLARE #StartDate DATETIME
DECLARE #EndDate DATETIME
SET #StartDate = '2014-12-22'
SET #EndDate = '2015-02-13'
drop table #TabCourseDetailID
SELECT ROW_NUMBER() OVER(ORDER BY CourseDetailID asc) AS Row,
CourseDetailID
into #TabCourseDetailID
from coursedetail
where UnitType='T' and courseID =1
Declare #counter as int
Declare #CourseDetailID varchar(500)
set #counter = 0
Declare #TempTable Table (FirstValue datetime,LastValue int)
while #StartDate <= #EndDate
begin
If DATEPART(WeekDay,#StartDate) IN (2,4,6)
begin
Set #Counter = #counter+1
Select #CoursedetailId=CoursedetailId
from #TabCourseDetailID
where row=#counter
insert into #TempTable (FirstValue,LastValue)
values (#StartDate,#CoursedetailId)
end
set #StartDate =DATEADD(d,1,#StartDate)
end
select t.LastValue,
t.FirstValue,
bp.conductedDate
from batchprogress bp
Join #TempTable t on (t.LastValue=bp.CoursedetailID)
where CourseID =1 and batchID =5
order by t.lastvalue
As I have From and To date. Something like below,
BeginDate End Date
1989-01-01 00:00:00.000 2015-12-31 00:00:00.000
I need to loop through until i get the list of all the Date's between those 2 (Begin & End Date's) records. I need to know what will be the efficient way of doing this. I have no clue on how to do this. Any help to this will be highly appreciated.
Thanks
This method uses a generated numbers table and is probably faster than looping.
DECLARE #BeginDate DATETIME = '19890101';
DECLARE #EndDate DATETIME = '20151231';
WITH
E1(N) AS ( SELECT 1 FROM ( VALUES (1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) DT(N)),
E2(N) AS ( SELECT 1 FROM E1 A, E1 B),
E4(N) AS ( SELECT 1 FROM E2 A, E2 B),
Numbers(N) AS
(
SELECT ROW_NUMBER() OVER ( ORDER BY ( SELECT NULL)) - 1 FROM E4
)
SELECT
N,
DATEADD(D, N, #BeginDate) AS TheDate
FROM Numbers
WHERE N <= DATEDIFF(D, #BeginDate, #EndDate)
You can do this with WHILE loop:
DECLARE #sdt DATE = '1989-01-01'
DECLARE #edt DATE = '2015-12-31'
WHILE #sdt <= #edt
BEGIN
PRINT #sdt
SET #sdt = DATEADD(dd, 1, #sdt )
END
Or with recursive CTE:
DECLARE #sdt DATE = '1989-01-01'
DECLARE #edt DATE = '2015-12-31';
WITH cte
AS ( SELECT #sdt AS sdt
UNION ALL
SELECT DATEADD(dd, 1, sdt)
FROM cte
WHERE DATEADD(dd, 1, sdt) <= #edt
)
SELECT *
FROM cte
OPTION ( MAXRECURSION 10000 )
There is also tally table method as in link provided by #Bridge
Actually the answer is tally tables. But if there is not a big interval the difference will be insignificant.
Something like this should work for your purposes:
DECLARE #sd date = '1989-01-01 00:00:00.000'
, #ed date = '2015-12-31 00:00:00.000'
DECLARE #tt TABLE(
[Date] date
)
WHILE(#sd <= #ed) --Loop which checks each iteration if the date has reached the end
BEGIN
INSERT INTO #tt
SELECT #sd AS Date
SET #sd = DATEADD(dd,1,#sd) --This willl increment the date so you actually advance the loop
END
SELECT * FROM #tt
I'm working on a query that deals with a frequency value (i.e. Mondays, Tuesdays, etc. - Think assignments).
So in my query I currently have a result of
jobId:1, personId:100, frequencyVal: 'Mondays'
jobId:2, personId:101, frequencyVal: 'Saturdays'
What I need is the next the 4 future(or current) dates for the frequencyVal.
So if today is 1/3/2015
I would need my result set to be
jobId:1, personId:100, frequencyVal: 'Mondays', futureDates: '1/5,1/12,1/19,1/26'
jobId:2, personId:102, frequencyVal: 'Saturdays', futureDates: '1/3,1/10,1/17,1/24'
I was looking at the following post:
How to find the Nearest (day of the week) for a given date
But that sets it for a specific date. And I'm looking at this being a web application and I want the dates for the current date. So if I try to run this query next Tuesday the future dates for jobId:1 would remove the 1/5 and add the 2/2.
Is there a way to pass in a weekday value to get the next nearest date?
I prefer a calendar table for this kind of query. Actually, I prefer a calendar table over date functions for most queries. Here's a minimal one. The one I use in production has more columns and more rows. (100 years of data is only 37k rows.)
create table calendar (
cal_date date not null primary key,
day_of_week varchar(15)
);
insert into calendar (cal_date) values
('2015-01-01'), ('2015-01-02'), ('2015-01-03'), ('2015-01-04'),
('2015-01-05'), ('2015-01-06'), ('2015-01-07'), ('2015-01-08'),
('2015-01-09'), ('2015-01-10'), ('2015-01-11'), ('2015-01-12'),
('2015-01-13'), ('2015-01-14'), ('2015-01-15'), ('2015-01-16'),
('2015-01-17'), ('2015-01-18'), ('2015-01-19'), ('2015-01-20'),
('2015-01-21'), ('2015-01-22'), ('2015-01-23'), ('2015-01-24'),
('2015-01-25'), ('2015-01-26'), ('2015-01-27'), ('2015-01-28'),
('2015-01-29'), ('2015-01-30'), ('2015-01-31'),
('2015-02-01'), ('2015-02-02'), ('2015-02-03'), ('2015-02-04'),
('2015-02-05'), ('2015-02-06'), ('2015-02-07'), ('2015-02-08'),
('2015-02-09'), ('2015-02-10'), ('2015-02-11'), ('2015-02-12'),
('2015-02-13'), ('2015-02-14'), ('2015-02-15'), ('2015-02-16'),
('2015-02-17'), ('2015-02-18'), ('2015-02-19'), ('2015-02-20'),
('2015-02-21'), ('2015-02-22'), ('2015-02-23'), ('2015-02-24'),
('2015-02-25'), ('2015-02-26'), ('2015-02-27'), ('2015-02-28')
;
update calendar
set day_of_week = datename(weekday, cal_date);
alter table calendar
alter column day_of_week varchar(15) not null;
alter table calendar
add constraint cal_date_matches_dow
check (datename(weekday, cal_date) = day_of_week);
create index day_of_week_ix on calendar (day_of_week);
Set the privileges so that
everyone can select, but
almost nobody can insert new rows, and
even fewer people can delete rows.
(Or write a constraint that can guarantee there are no gaps. I think you can do that in SQL Server.)
You can select the next four Mondays after today with a very simple SQL statement. (The current date is 2015-01-05, which is a Monday.)
select top 4 cal_date
from calendar
where cal_date > convert(date, getdate())
and day_of_week = 'Monday'
order by cal_date;
CAL_DATE
--
2015-01-12
2015-01-19
2015-01-26
2015-02-02
For me, this is a huge advantage. No procedural code. Simple SQL that is obviously right. Big win.
Your sample table
create table #t
(
jobId int,
personId int,
frequencyVal varchar(10)
);
insert into #t values (1,100,'Mondays'),(2,101,'Saturdays');
QUERY 1 : Select nearest 4 week of days in current month for particular week day
-- Gets first day of month
DECLARE #FIRSTDAY DATE=DATEADD(month, DATEDIFF(month, 0, GETDATE()), 0)
;WITH CTE as
(
-- Will find all dates in current month
SELECT CAST(#FIRSTDAY AS DATE) as DATES
UNION ALL
SELECT DATEADD(DAY,1,DATES)
FROM CTE
WHERE DATES < DATEADD(MONTH,1,#FIRSTDAY)
)
,CTE2 AS
(
-- Join the #t table with CTE on the datename+'s'
SELECT jobId,personId,frequencyVal,DATES,
-- Get week difference for each weekday
DATEDIFF(WEEK,DATES,GETDATE()) WEEKDIFF,
-- Count the number of weekdays in a month
COUNT(DATES) OVER(PARTITION BY DATENAME(WEEKDAY,CTE.DATES)) WEEKCOUNT
FROM CTE
JOIN #t ON DATENAME(WEEKDAY,CTE.DATES)+'s' = #t.frequencyVal
WHERE MONTH(DATES)= MONTH(GETDATE())
)
-- Converts to CSV and make sure that only nearest 4 week of days are generated for month
SELECT DISTINCT C2.jobId,C2.personId,frequencyVal,
SUBSTRING(
(SELECT ', ' + CAST(DATEPART(MONTH,DATES) AS VARCHAR(2)) + '/' +
CAST(DATEPART(DAY,DATES) AS VARCHAR(2))
FROM CTE2
WHERE C2.jobId=jobId AND C2.personId=personId AND C2.frequencyVal=frequencyVal AND
((WEEKDIFF<3 AND WEEKDIFF>-3 AND WEEKCOUNT = 5) OR WEEKCOUNT <= 4)
ORDER BY CTE2.DATES
FOR XML PATH('')),2,200000) futureDates
FROM CTE2 C2
SQL FIDDLE
For example, in Query2 the nearest date(here we take example as Saturday) of
2015-Jan-10 will be 01/03,01/10,01/17,01/24
2015-Jan-24 will be 01/10,01/17,01/24,01/31
QUERY 2 : Select next 4 week's dates for particular week day irrelevant of month
;WITH CTE as
(
-- Will find the next 4 week details
SELECT CAST(GETDATE() AS DATE) as DATES
UNION ALL
SELECT DATEADD(DAY,1,DATES)
FROM CTE
WHERE DATES < DATEADD(DAY,28,GETDATE())
)
,CTE2 AS
(
-- Join the #t table with CTE on the datename+'s'
SELECT jobId,personId,frequencyVal, DATES,
ROW_NUMBER() OVER(PARTITION BY DATENAME(WEEKDAY,CTE.DATES) ORDER BY CTE.DATES) DATECNT
FROM CTE
JOIN #t ON DATENAME(WEEKDAY,CTE.DATES)+'s' = #t.frequencyVal
)
-- Converts to CSV and make sure that only 4 days are generated for month
SELECT DISTINCT C2.jobId,C2.personId,frequencyVal,
SUBSTRING(
(SELECT ', ' + CAST(DATEPART(MONTH,DATES) AS VARCHAR(2)) + '/' +
CAST(DATEPART(DAY,DATES) AS VARCHAR(2))
FROM CTE2
WHERE C2.jobId=jobId AND C2.personId=personId AND C2.frequencyVal=frequencyVal
AND DATECNT < 5
ORDER BY CTE2.DATES
FOR XML PATH('')),2,200000) futureDates
FROM CTE2 C2
SQL FIDDLE
The following would be the output if the GETDATE() (if its Saturday) is
2015-01-05 - 1/10, 1/17, 1/24, 1/31
2015-01-24 - 1/24, 1/31, 2/7, 2/14
There's no built-in function to do it. But you can try this, you may place it inside a Scalar-Valued Function:
DECLARE #WeekDay VARCHAR(10) = 'Monday';
DECLARE #WeekDayInt INT;
SELECT #WeekDayInt = CASE #WeekDay
WHEN 'SUNDAY' THEN 1
WHEN 'MONDAY' THEN 2
WHEN 'TUESDAY' THEN 3
WHEN 'WEDNESDAY' THEN 4
WHEN 'THURSDAY' THEN 5
WHEN 'FRIDAY' THEN 6
WHEN 'SATURDAY' THEN 7 END
SELECT CONVERT(DATE, DATEADD(DAY, (DATEPART(WEEKDAY, GETDATE()) + #WeekDayInt) % 7, GETDATE())) AS NearestDate
UPDATE:
Looks like radar was right, here's the solution:
DECLARE #WeekDay VARCHAR(10) = 'Monday';
DECLARE #WeekDayInt INT;
DECLARE #Date DATETIME = GETDATE();
SELECT #WeekDayInt = CASE #WeekDay
WHEN 'SUNDAY' THEN 1
WHEN 'MONDAY' THEN 2
WHEN 'TUESDAY' THEN 3
WHEN 'WEDNESDAY' THEN 4
WHEN 'THURSDAY' THEN 5
WHEN 'FRIDAY' THEN 6
WHEN 'SATURDAY' THEN 7 END
DECLARE #Diff INT = DATEPART(WEEKDAY, #Date) - #WeekDayInt;
SELECT CONVERT(DATE, DATEADD(DAY, CASE WHEN #Diff >= 0 THEN 7 - #Diff ELSE ABS(#Diff) END, #Date)) AS NearestDate
Try this - based on king.code's answer to get the nearest date.
create table #t
(
jobId int,
personId int,
frequencyVal varchar(10)
);
insert into #t values (1,100,'Mondays'),(2,101,'Saturdays');
WITH cte(n) AS
(
SELECT 0
UNION ALL
SELECT n+1 FROM cte WHERE n < 3
)
select #t.jobId, #t.personId, #t.frequencyVal, STUFF(a.d, 1, 1, '') AS FutureDates
from #t
cross apply (SELECT CASE #t.frequencyVal
WHEN 'SUNDAYS' THEN 1
WHEN 'MONDAYS' THEN 2
WHEN 'TUESDAYS' THEN 3
WHEN 'WEDNESDAYS' THEN 4
WHEN 'THURSDAYS' THEN 5
WHEN 'FRIDAYS' THEN 6
WHEN 'SATURDAYS' THEN 7
END)tranlationWeekdays(n)
cross apply (select ',' + CONVERT(varchar(10), CONVERT(date,dateadd(WEEK, cte.n,CONVERT(DATE, DATEADD(DAY, (DATEPART(WEEKDAY, GETDATE()) + tranlationWeekdays.n) % 7, GETDATE()))))) from cte FOR XML PATH('')) a(d);
drop table #t;
Try this,
DECLARE #YEAR INT=2015
DECLARE #MONTH INT=1
DECLARE #DAY INT=1
DECLARE #DATE DATE = (SELECT DateFromParts(#Year, #Month, #Day))
DECLARE #TOTAL_DAYS INT =(SELECT DatePart(DY, #DATE));
WITH CTE1
AS (SELECT T_DAY=(SELECT DateName(DW, #DATE)),
#DATE AS T_DATE,
#DAY AS T_DDAY
UNION ALL
SELECT T_DAY=(SELECT DateName(DW, DateAdd(DAY, T_DDAY + 1, #DATE))),
DateAdd(DAY, T_DDAY + 1, #DATE) AS T_DATE,
T_DDAY + 1
FROM CTE1
WHERE T_DDAY + 1 <= 364)
SELECT DISTINCT T_DAY,
Stuff((SELECT ',' + CONVERT(VARCHAR(30), T_DATE)
FROM CTE1 A
WHERE A.T_DAY=CTE1.T_DAY AND A.T_DATE > GetDate() AND A.T_DATE<(DATEADD(WEEK,4,GETDATE()))
FOR XML PATH('')), 1, 1, '') AS FUTURE
FROM CTE1
ORDER BY T_DAY
OPTION (MAXRECURSION 365)
This is a simpler way I think, and I think it fits your requirements.
Note that I have changed your frequency_val column to an integer that represents the day of the week from SQL servers perspective and added a calculated column to illustrate how you can easily derive the day name from that.
declare #t table
(
jobId int,
personId int,
--frequencyVal varchar(10)
frequency_val int,
frequency_day as datename(weekday,frequency_val -1) + 's'
);
declare #num_occurances int = 4
declare #from_date date = dateadd(dd,3,getdate()) -- this will allow you to play with the date simply by changing the increment value
insert into #t
values
(1,100,1),--'Mondays'),
(2,101,6),--'Saturdays');
(3,101,7),--'Saturdays');
(4,100,2)--'Mondays'),
--select * from #t
;with r_cte (days_ahead, occurance_date)
as (select 0, convert(date,#from_date,121)
union all
select r_cte.days_ahead +1, convert(date,dateadd(DD, r_cte.days_ahead+1, #from_date),121)
from r_cte
where r_cte.days_ahead < 7 * #num_occurances
)
select t.*, r_cte.occurance_date
from
#t t
inner join r_cte
on DATEPART(WEEKDAY, dateadd(dd,##DATEFIRST - 1 ,r_cte.occurance_date)) = t.frequency_val
Having seen the use of DATENAME in some of the answers already given, I'd like to point out that return values of DATENAME might vary depending on your current language setting, but you can save the current language setting and ensure usage of us_english so you can be confident to use English weekday names.
Now here is my slightly different approach to get the 4 next dates that fall on a certain (known) weekday, using a user defined table valued function that allows to create a number sequence table (yes this is a pretty dull function, you have to pass MaxValue greater MinValue, but that could be easily enhanced, if needed, but hey, it does the job). Using that function span a table over 28 values (next 28 days should indeed include the next 4 relevant weekdays ;)), apply DATEADD on GETDATE and reduce the result set with WHERE to only those values that have the right weekday:
CREATE FUNCTION GetIntSequence(#MinValue INT, #MaxValue INT)
RETURNS #retSequence TABLE
(
IntValue INT NOT NULL
)
BEGIN
DECLARE #i INT = (SELECT #MinValue)
WHILE #i <= #MaxValue
BEGIN
INSERT INTO #retSequence (IntValue) SELECT #i
SELECT #i = #i + 1
END
RETURN
END
GO
DECLARE #weekDay NVARCHAR(MAX) = 'Monday' --(or Tuesday, wednesday, ...)
--save current language setting
DECLARE #languageBackup NVARCHAR(MAX) = (SELECT ##LANGUAGE)
--ensure us english language setting for reliable weekday names
SET LANGUAGE us_english;
SELECT FourWeeks.SomeDay FROM
(
SELECT
DATEADD(DAY, IntValue, GETDATE()) AS SomeDay
FROM dbo.GetIntSequence(1, 28)
) AS FourWeeks
WHERE DATENAME(WEEKDAY, SomeDay) = #weekDay
--restore old language setting
SET LANGUAGE #languageBackup;
GO
DROP FUNCTION dbo.GetIntSequence