Matt Miller (#4) (1/16/2014)
by the way - you will want to incorporate the event_date into the ORDER BY, otherwise the row_number() will essentially assign numbers within a group ad-hoc (i.e. not exactly "at random", but it won't always assign the numbers in the same way). So just make sure that whatever you're using the ORDER BY gives you a good enough ordering (so that if it does include multiple entries with the same ORDER BY "key", you're comfortable with any of them being the one being returned).
To add a little bit more, the columns CarMake and Country are not needed in the ORDER BY because they're in the PARTITION BY.