Find intersections in date ranges and concatenate aggregated labels

Question

Hello All,
The original source of data will be a table of persons with their member ship:
Description StartDate EndDate
18 Smith John Poker Club 01/01/2009 NULL
18 Smith John Library 05/01/2009 18/01/2009
18 Smith John Gym 10/01/2009 28/01/2009
26 Adams Jane Pilates 03/01/2009 16/02/2009
The challenge will be to find each intersection of membership date ranges for each person and produce for this each unique range:
a new line with the StartDate and EndDate of the range
Concatenate in the description the descriptions of the memberships for this range with:
“/” as separator
order by membership StartDate
This is the table of results expected:
18 Smith John Poker Club 01/01/2009 04/01/2009
18 Smith John Poker Club / Library 05/01/2009 09/01/2009
18 Smith John Poker Club / Library / Gym 10/01/2009 18/01/2009
18 Smith John Poker Club / Gym 19/01/2009 28/01/2009
18 Smith John Poker Club 29/01/2009 NULL
26 Adams Jane Pilates 03/01/2009 16/02/2009
Sample Script:
SET DATEFORMAT dmy
DECLARE @Membership TABLE (
PersonID int,
Surname nvarchar(16),
FirstName nvarchar(16),
Description nvarchar(16),
StartDate datetime,
EndDate datetime)
INSERT INTO @Membership VALUES (18, 'Smith', 'John',
'Poker Club', '01/01/2009', NULL)
INSERT INTO @Membership VALUES (18, 'Smith', 'John',
'Library', '05/01/2009', '18/01/2009')
INSERT INTO @Membership VALUES (18, 'Smith', 'John',
'Gym', '10/01/2009', '28/01/2009')
INSERT INTO @Membership VALUES (26, 'Adams', 'Jane',
'Pilates', '03/01/2009', '16/02/2009')
Note:Make sure that your solution uses a single query that starts either with "SELECT" or "WITH" or ";WITH".
Can you please share suggestions.
Regards,
Vaishu

Answer 1

This query
;WITH RS AS -- RangeStart
SELECT PersonID, StartDate AS RangeStart
FROM @Membership
UNION
SELECT PersonID, DATEADD(day, 1, EndDate) AS RangeStart
FROM @Membership
WHERE EndDate IS NOT NULL
RE AS -- RangeEnd
SELECT PersonID, DATEADD(day, -1, StartDate) AS RangeEnd
FROM @Membership
WHERE StartDate IS NOT NULL
UNION
SELECT PersonID, EndDate AS RangeEnd
FROM
@Membership
R AS -- Ranges
SELECT RS.PersonID, RS.RangeStart, RE.RangeEnd
FROM
RS CROSS APPLY
SELECT TOP (1) RE.RangeEnd
FROM RE
WHERE
RE.PersonID = RS.PersonID
AND (
RE.RangeEnd >= RS.RangeStart
OR RS.RangeStart IS NOT NULL AND RE.RangeEnd IS NULL
ORDER BY
ISNULL(RE.RangeEnd, '99991231')
) RE
SELECT R.*,
STUFF( (
SELECT '/' + m.Description
FROM
@Membership m
WHERE
m.PersonID = R.PersonID
AND (m.StartDate <= R.RangeEnd OR R.RangeEnd IS NULL) AND (m.EndDate >= R.RangeStart OR m.EndDate IS NULL)
FOR XML PATH('')
1, 1, '') AS Description
FROM
R
Returns this result:
PersonID
RangeStart
RangeEnd
Description
18
2009-01-01
2009-01-04
Poker Club
18
2009-01-05
2009-01-09
Poker Club/Library
18
2009-01-10
2009-01-18
Poker   Club/Library/Gym
18
2009-01-19
2009-01-28
Poker Club/Gym
18
2009-01-29
NULL
Poker Club
26
2009-01-03
2009-02-16
Pilates
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