Retrieving the most recent records within a query

Question

I have the following tables:

tblPerson:

PersonID | Name
---------------------
   1     | John Smith
   2     | Jane Doe
   3     | David Hoshi
         


        

Answer 1

As @Mark Byers mentions, this problem comes up frequently on Stack Overflow.

Here's the solution I most frequently recommend, given your tables:

SELECT p.*, l1.*
FROM tblPerson p
JOIN tblLocation l1 ON p.PersonID = l1.PersonID
LEFT OUTER JOIN tblLocation l2 ON p.PersonID = l2.PersonID AND 
  (l1.timestamp < l2.timestamp OR l1.timestamp = l2.timestamp AND l1.LocationId < l2.LocationId)
WHERE l2.LocationID IS NULL;

To see other examples, follow the tag greatest-n-per-group, which I added to your question.