find out data types using sql or php

Hey guys. This is probably a n00b question, but here goes anyway.

I have a set of csv files that I COPY t o a number of import tables
(same field layout as live tables, but with all datatypes 'text') then
use an INSERT INTO ... SELECT FROM statement to transfer the rows over
to the live table (at times filtering out, at times not). Unfortunately
if any of the data is not type perfect (letters in number fields, etc.)
then the entire query bombs and nothing gets loaded. What I'd like to do
is add a field is_ok and then use sql or php (or whatever else, if
there's an easier way) to determine the field datatype (text, numeric,
bool, etc.) and then use some regex or something along those lines to
attempt to verify that the data is good, and then mark the is_ok field
(obviously a bool) as true, and use is_ok = TRUE in the insert/select
statement. Can somebody give me a push in the right direction?