Question

I have a table with the following structure

ID  Person  LOG_TIME
-----------------------------------
1   1       2012-05-21 13:03:11.550
2   1       2012-05-22 13:09:37.050 <--- this is duplicate
3   1       2012-05-28 13:09:37.183
4   2       2012-05-20 15:09:37.230
5   2       2012-05-22 13:03:11.990 <--- this is duplicate
6   2       2012-05-24 04:04:13.222 <--- this is duplicate
7   2       2012-05-29 11:09:37.240

I have some application job that fills this table with data.

There is a business rule that each person should have only 1 record in every 7 days.

From the above example, records # 2,5 and 6 are considered duplicates while 1,3,4 and 7 are OK.

I want to have a SQL query that checks if there are records for the same person in less than 7 days.

Answer 1

;WITH cte AS
 (
  SELECT ID, Person, LOG_TIME,
         DATEDIFF(d, MIN(LOG_TIME) OVER (PARTITION BY Person), LOG_TIME) AS diff_date
  FROM dbo.Log_time
  )
SELECT *
FROM cte
WHERE diff_date BETWEEN 1 AND 6

Demo on SQLFiddle