Question

I need to do something in SQL and I’m currently confused!

So I have something like this:

idEvent   idService   dateCreated
-------   ---------   -----------
1         1           2012-01-01
2         1           2012-02-02
3         2           2012-01-01
4         2           2012-02-02

The idEvent is auto-incrementing.

What I need to get is the biggest row (ordered by dateCreated DESC) for each idService.

So I’d need to get this as a result :

idEvent
-------
2
4

Answer 1

You can use a common table expression to apply a “row number” to each idService / dateCreated combination. You didn’t specify your table name, so you’ll have to fix that.

;WITH x AS 
(
  SELECT idEvent, idService, dateCreated, rn = ROW_NUMBER() OVER 
    (PARTITION BY idService ORDER BY dateCreated DESC)
  FROM dbo.table_something_like_this
)
SELECT idEvent, idService, dateCreated
FROM x
WHERE rn = 1;