General Discusson: use framework or sql for web application?

I've just had the experience of one of my perl/php/postgres prototypes
failing to make it to a bigger version of the same app. Part of the
reason is because of some specification issues. The other may be because
of the complications of modelling the data in a java framework (expresso
in this case) which meant that things like left outer joins in my
original database interface file (perl using dbi) were replaced by
constructing software objects from simple database calls.

I'm about to embark on another medium-sized web application and would be
grateful for general views on whether or not it is considered good
practice to either:

model data in the database, providing views or functions to access
particular sets of data.
OR
model data in the "middleware zone", with quoted sql used to access data
in an ad hoc manner.

--
Rory Campbell-Lange
<rory(at)campbell-lange(dot)net>
<www.campbell-lange.net>