Question

I have a table with a unique id field, a userid field, and a date field.

What I want to do is have a column which flags if there is a record in the next 28 days with the same userid.

It is only the future i’m looking at, not past records..

id | uid | date       | future
1  | 342 | 23/10/2007 | 1
2  | 342 | 3/11/2007  | 0
3  | 342 | 20/2/2009  | 0
4  | 147 | 22/2/2009  | 0

This is a basic example of the result i’m after.

I’m using mssql 2008

Answer 1

The following query would return the rows matching your requirement. If you want to, you could create a view from this query so that you could run other queries on just the future rows.

SELECT id, uid, date FROM orders current
WHERE EXISTS 
(
    SELECT * from orders future 
    WHERE future.date < DateAdd(DAYS, 28, current.date)
    AND future.date > getdate()
    AND future.uid = current.uid
)