SQL-Server Get data of each day that falls between two dates - sql-server

Question

I have a table with job schedules :
job_id [unique ID]
pref_start [date]
spec_duration [time in seconds]
I can calculate the end date from the preferred start and duration. The pref_start is not fixed, and can be changed at whim by the engineers.
I need to report activity in any given week, so if I have data similar to:
jid start end
J1 01/01/yyyy 15/02/yyyy
J2 07/01/yyyy 08/02/yyyy
J3 09/02/yyyy 21/03/yyyy
How would I query "tell me the job id's that occur on each day of the week 07/02/yyyy to 12/02/yyyy"

Answer 1

First find the matching intervals between your jobs and your filtering interval, then the amount of days for the filter interval and the overlapping intervals must match:
DECLARE #Jobs TABLE (
ID INT IDENTITY,
StartDate DATE,
EndDate DATE)
INSERT INTO #Jobs (
StartDate,
EndDate)
VALUES
('2019-01-01', '2019-02-15'),
('2019-01-07', '2019-02-08'),
('2019-02-09', '2019-03-21')
DECLARE #FilterStartDate DATE = '2019-02-07'
DECLARE #FilterEndDate DATE = '2019-02-12'
;WITH AtLeast1DayOverlappingJobs AS
(
SELECT
J.ID,
J.StartDate,
J.EndDate,
OverlappingStartDate = CASE
WHEN J.StartDate > #FilterStartDate THEN J.StartDate ELSE #FilterStartDate END, -- Highest of 2
OverlappingEndDate = CASE
WHEN J.EndDate < #FilterEndDate THEN J.EndDate ELSE #FilterEndDate END -- Lowest of 2
FROM
#Jobs AS J
WHERE
-- They share at least 1 day
#FilterStartDate <= J.EndDate AND #FilterEndDate >= J.StartDate
)
SELECT
T.*
FROM
AtLeast1DayOverlappingJobs AS T
WHERE
-- Amount of days must match between filter and overlapping periods
DATEDIFF(DAY, #FilterStartDate, #FilterEndDate) = DATEDIFF(DAY, T.OverlappingStartDate, T.OverlappingEndDate)
Results:
ID StartDate EndDate OverlappingStartDate OverlappingEndDate
1 2019-01-01 2019-02-15 2019-02-07 2019-02-12