Drive EndDate of Current Row From StarDate of Next Row - tsql

Question

Can some one please help me with how to create end date from start date.
Products referred to a company for testing while the product with the company they carry out multiple tests on different dates and record the test date to establish the product condition i.e. (outcomeID).
I need to establish the StartDate which is the testDate and EndDate which is the start date of the next row. But if multiple consecutive tests resulted in the same OutcomeID I need to return only one row with the StartDate of the first test and the end date of the last test. In another word if the outcomeID did not change over a few consecutive tests.
Here is my data set
DECLARE #ProductTests TABLE
(
RequestID int not null,
ProductID int not null,
TestID int not null,
TestDate datetime null,
OutcomeID int
)
insert into #ProductTests
(RequestID ,ProductID ,TestID ,TestDate ,OutcomeID )
select 1,2,22,'2005-01-21',10
union all
select 1,2,42,'2007-03-17',10
union all
select 1,2,45,'2010-12-25',10
union all
select 1,2,325,'2011-01-14',13
union all
select 1,2,895,'2011-08-10',15
union all
select 1,2,111,'2011-12-23',15
union all
select 1,2,636,'2012-05-02',10
union all
select 1,2,554,'2012-11-08',17
--select *from #producttests
RequestID ProductID TestID TestDate OutcomeID
1 2 22 2005-01-21 10
1 2 42 2007-03-17 10
1 2 45 2010-12-25 10
1 2 325 2011-01-14 13
1 2 895 2011-08-10 15
1 2 111 2011-12-23 15
1 2 636 2012-05-02 10
1 2 554 2012-11-08 17
And this is what I need to achieve.
RequestID ProductID StartDate EndDate OutcomeID
1 2 2005-01-21 2011-01-14 10
1 2 2011-01-14 2011-08-10 13
1 2 2011-08-10 2012-05-02 15
1 2 2012-05-02 2012-11-08 10
1 2 2012-11-08 NULL 17
As you see from the dataset the first three tests (22, 42, and 45) all resulted in OutcomeID 10 so in my result I only need start date of test 22 and end date of test 45 which is the start date of test 325.As you see in test 636 outcomeID has gone back to 10 from 15 so it needs to be returned too.
--This is what I have managed to achieve at the moment using the following script
select T1.RequestID,T1.ProductID,T1.TestDate AS StartDate
,MIN(T2.TestDate) AS EndDate ,T1.OutcomeID
from #producttests T1
left join #ProductTests T2 ON T1.RequestID=T2.RequestID
and T1.ProductID=T2.ProductID and T2.TestDate>T1.TestDate
group by T1.RequestID,T1.ProductID ,T1.OutcomeID,T1.TestDate
order by T1.TestDate
Result:
RequestID ProductID StartDate EndDate OutcomeID
1 2 2005-01-21 2007-03-17 10
1 2 2007-03-17 2010-12-25 10
1 2 2010-12-25 2011-01-14 10
1 2 2011-01-14 2011-08-10 13
1 2 2011-08-10 2011-12-23 15
1 2 2011-12-23 2012-05-02 15
1 2 2012-05-02 2012-11-08 10
1 2 2012-11-08 NULL 17

Answer 1

nov 7 but still not answered
so here is my solution
not soo pretty but works
my hint is read about windowing , ranking and aggregate functions like row_number, rank , avg, sum etc.
those are essential when you want to write raports , and becoming quite powerfull in sql server 2012
i have also used CTE (common table expression) but it can be written as subquery or temporary table
;with cte ( ida, requestid, productid, testid, testdate, outcomeid) as
(
-- select rows where the outcome id is changing
select b.* from
(select ROW_NUMBER() over( partition by requestid, productid order by testDate) as id, * from #ProductTests)a
right outer join
(select ROW_NUMBER() over(partition by requestid, productid order by testDate) as id, * from #ProductTests) b
on a.requestID = b.requestID and a.productID = b.productID and a.id +1 = b.id
where 1=1
--or a.id = 1
and a.outcomeid <> b.outcomeid or b.outcomeid is null or a.id is null
)
select --*
a.RequestID,a.ProductID,a.TestDate AS StartDate ,MIN(b.TestDate) AS EndDate ,a.OutcomeID
from cte a left join cte b on a.requestid = b.requestid and a.productid = b.productid and a.testdate < b.testdate
group by a.RequestID,a.ProductID ,a.OutcomeID,a.TestDate
order by StartDate

Answer 2

Actually, there seem to be two problems in your question. One is how to group sequential (based on specific criteria) rows containing the same value. The other is the one actually spelled out in your title, i.e. how to use the next row's StartDate as the current row's EndDate.
Personally, I would solve these two problems in the order I mentioned them, so I would first address the grouping problem. One way to group the data properly in this case would be to use double ranking like this:
WITH partitioned AS (
SELECT
*,
grp = ROW_NUMBER() OVER (PARTITION BY RequestID, ProductID ORDER BY TestDate)
- ROW_NUMBER() OVER (PARTITION BY RequestID, ProductID, OutcomeID ORDER BY TestDate)
FROM #ProductTests
)
, grouped AS (
SELECT
RequestID,
ProductID,
StartDate = MIN(TestDate),
OutcomeID
FROM partitioned
GROUP BY
RequestID,
ProductID,
OutcomeID,
grp
)
SELECT *
FROM grouped
;
This should give you the following output for your data sample:
RequestID ProductID StartDate OutcomeID
--------- --------- ---------- ---------
1 2 2005-01-21 10
1 2 2011-01-14 13
1 2 2011-08-10 15
1 2 2012-05-02 10
1 2 2012-11-08 17
Obviously, one thing is still missing, and it's EndDate, and now is the right time to care about it. Use ROW_NUMBER() once again, to rank the result set of the grouped CTE, then use the rankings in the join condition when joining the result set with itself (using an outer join):
WITH partitioned AS (
SELECT
*,
grp = ROW_NUMBER() OVER (PARTITION BY RequestID, ProductID ORDER BY TestDate)
- ROW_NUMBER() OVER (PARTITION BY RequestID, ProductID, OutcomeID ORDER BY TestDate)
FROM #ProductTests
)
, grouped AS (
SELECT
RequestID,
ProductID,
StartDate = MIN(TestDate),
OutcomeID,
rnk = ROW_NUMBER() OVER (PARTITION BY RequestID, ProductID ORDER BY MIN(TestDate))
FROM partitioned
GROUP BY
RequestID,
ProductID,
OutcomeID,
grp
)
SELECT
g1.RequestID,
g1.ProductID,
g1.StartDate,
g2.StartDate AS EndDate,
g1.OutcomeID
FROM grouped g1
LEFT JOIN grouped g2
ON g1.RequestID = g2.RequestID
AND g1.ProductID = g2.ProductID
AND g1.rnk = g2.rnk - 1
;
You can try this query at SQL Fiddle to verify that it returns the output you are after.