SQL Query to find previous records
I am struggling to write a query based on the table below that should get Bad records for a Location (where BadRec =1) and also previous 3 records(Max) on that Location including bad records;
TranDate Location BadRec
======================= ======== ======
2010-08-25 00:00:00.000 STN-2 0
2010-08-26 00:00:00.000 STN-2 1
2010-08-27 00:00:00.000 STN-1 1
2010-08-28 00:00:00.000 STN-1 0
2010-08-28 00:00:00.000 STN-2 1
2010-08-29 00:00:00.000 STN-1 0
2010-08-30 00:00:00.000 STN-1 1
2010-08-31 00:00:00.000 STN-1 0
2010-09-01 00:00:00.000 STN-1 0
Here is the expected out Put;
TranDate Location BadRec comments
======================= ======== ====== ========
2010-08-30 00:00:00.000 STN-1 1 <- Bad record on STN-1
2010-08-29 00:00:00.000 STN-1 0 <- First Previous record
2010-08-28 00:00:00.000 STN-1 0 <- Second Previous record
2010-08-27 00:00:00.000 STN-1 1 <- Third Previous record (Previous include bad rec)
2010-08-28 00:00:00.000 STN-2 1 <- Bad record on STN-2
2010-08-26 00:00:00.000 STN-2 1
2010-08-25 00:00:00.000 STN-2 0
2010-08-27 00:00:00.000 STN-1 1 <- Bad record on STN-1,No previous record for this
2010-08-开发者_StackOverflow中文版26 00:00:00.000 STN-2 1 <- Bad record on STN-2
2010-08-25 00:00:00.000 STN-2 0
Is this possible to write this using a single query?? Using CTE?? Over (partition…)?? Any help is well appreciated. Note: I am on a SQL 2005 machine;
Does this do what you want?
SELECT TranDate, Location, BadRec
FROM
(
SELECT pr.TranDate, pr.Location, pr.BadRec,
ROW_NUMBER() OVER (PARTITION BY r.TranDate ORDER BY pr.TranDate DESC) AS SEQUENCE
FROM Records r
JOIN Records pr ON r.Location = pr.Location
AND r.TranDate >= pr.TranDate
WHERE r.BadRec = 1
) x
WHERE SEQUENCE <= 4
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