From: "DePhillips, Michael P"
> Am I gaining anything by using a timestamp instead of using dateTime and
> calling now(), for example, increased performance, better indexing, etc.
> I guess another way to ask this is does the MySQL internals handle a
> timestamp more efficiently than a dateTime.
I haven't seen much difference in performance; in fact I think you'll lose
standard human readable output (I still can't read UNIX timestamps), you'll
lose a large range of dates, etc.
You'll probably gain more by optimizing the query and expressions, designing
the right indexes, etc.