deejay - 8:00 pm on Oct 5, 2010 (gmt 0)

DOesn't work in this case Enigma1, as I need all matches, not just one, but only the match where the previous date is immediately prior to the current date.

Yeah, I know.. I confuse myself too.

The query example I gave will produce a result with X rows that matches

Current = Previous
2008-12-04 = 2008-11-20
2009-01-12 = 2008-11-20
2009-01-12 = 2008-12-04
2009-02-04 = 2008-11-20
2009-02-04 = 2008-12-04
2009-02-04 = 2009-01-12

The result set I need to get to is:

Current = Previous
2008-12-04 = 2008-11-20
2009-01-12 = 2008-12-04
2009-02-04 = 2009-01-12

.. of course with the correct readings alongside.

Does that help?