Parameter checking on an interfase

[w.m.gardella.sambeth at gmail.com]

Hi all,
        I am more or less new to Python, and currently am making my
first "serious" program. The application is a Clinical History manager
(for my wife) which stores its data on a sqlite database. After
googling on this newsgroup, I have read several threads where is
stated that the LBYL way of testing parameters is not a pythonic way
to work, and that is preferable catch the exceptions generated trying
to use an invalid parameter passed to a function.
        Although I am generally following this approach, the problem I
see is that sqlite docs states clearly that the engine does not check
that the data types passed to the SQL sentences matches the types
declared for the column, and lets any kind of information to be put in
any column of the table. When I code the "business objects" of the
application (don't know if this is the exact term for a layer that
will isolate the application from the raw database, letting me change
it in a future if necessary), I realize that if I pass arguments of
wrong type (say, a numeric ID instead of the patient name), the DB
engine will accept that gladly, and I will finish with data that could
not be consistently retrievable if I use the DB from another program
(no one right now, but I think of, perhaps, statistical trends on
diseases and treatments).
        In this case, could be reasonable add type checking LBYL style
on the methods, so if passed data is of wrong type, it generates a
adequate exception to be catched by the caller? In this way, the rest
of the app (mostly GUI) can be coded EAFP style. As programming
background, as you can guess, I have made some programming in C, VBA
and JavaScript (quite procedurally).
        I hope that you can bring me some light about this kind of
design, so I can improve my coding and get the Python way faster.
Cheers!
           Walter Gardella
PS: Excuse me if my english is not good enough, but is not my mother
tongue (I'm argentinian), and if my computerish is flawed (I'm only
human;))