How to repeat a pattern in SQL skipping weekends? - sql

Question

I have a table with a column patterns something like '1,2,3,4' and a column name frequency which represents how many times each pattern shall repeat. For ex.
I have a generated a pattern but not able to skip weekends, here is my current code -
;WITH TestCteNew (EmployeeId, ShiftId, StartDate, Enddate)AS (
SELECT
employeeid.n.query('.[1]').value('.', 'INT') EmployeeId,
shiftid.n.query('.[1]').value('.', 'INT') ShiftId
,StartDate, Enddate
FROM
TestCte
CROSS APPLY employeeid.nodes('x') AS employeeid(n)
CROSS APPLY shiftid.nodes('x') AS shiftid(n)
CROSS APPLY (SELECT TOP(2) ROW_NUMBER() OVER(ORDER BY (SELECT NULL))-1 r_num FROM SYS.ALL_OBJECTS A , SYS.ALL_OBJECTS B) X)
,TestCteFinal(EmployeeId, ShiftId, SDate,r_num) AS (
SELECT EmployeeId, ShiftId, StartDate + ROW_NUMBER() OVER (PARTITION BY EmployeeId ORDER BY r_num)-1 AS SD, x.r_num
FROM TestCteNew
CROSS APPLY (SELECT TOP(2) ROW_NUMBER() OVER(ORDER BY (SELECT NULL))-1 r_num FROM SYS.ALL_OBJECTS A , SYS.ALL_OBJECTS B) X)
With the above code I am able to generate something like below
Account DayOfWeek Shifts Shifts
1 20201007 100 1
2 20201107 100 1 (Saturday)
3 20201207 100 2 (Sunday)
4 20201307 100 2
5 20201407 100 3
6 20201507 100 3
7 20201607 100 4
8 20201707 100 4
...Same set of records above once again
Here the issue is my pattern is not skipping weekends, I want something like below.
DECLARE #Pattern VARCHAR(10)= '1,2,3,4', #Frequency INT=2
Account DayOfWeek Shifts Shifts
1 20201007 100 1
2 20201107 100 0 (Saturday)
3 20201207 100 0 (Sunday)
4 20201307 100 1
5 20201407 100 2
6 20201507 100 2
7 20201607 100 3
8 20201707 100 3
9 20201807 100 0 (Saturday)
10 20201907 100 0 (Sunday)
12 20202007 100 4
13 20202107 100 4
14 20202207 100 1
15 20202307 100 1
I want to repeat the pattern in the above defined format.

Answer 1

This is pseudo-code because you the source of the data isn't clear. You refer to a TestCte that isn't defined. The query never uses the #Frequency and #Pattern variables that head the desired outer. The output has an Account column that isn't mentioned anywhere else... But perhaps this approach will work better.
declare #Frequency int = 2;
declare #StartDt date = '20200710';
with num(n) as (
select top (256) row_number() over (order by (select null)) - 1
from sys.all_objects
), dates(n, dt) as (
select row_number() over (order by n), dateadd(day, n, #StartDt)
from num
-- filter weekend dates
where datepart(weekday, dateadd(day, n, #StartDt)) between 1 and 5
)
select p.n, r.n, d.dt
from
patterns as p -- this comes from xml? I'm going to assume these are numbered somehow
inner join num as r /* repetitions */
on r.n <= #Frequency -- I think something like "multiples" might be a better name
inner join dates as d
on d.n = #Frequency * p.n + r.n