Changing column names in tables 2

["Tony Cade" <arcade646@xxxxxxxxxxxxxx>]

Sorry about the earlier incomplete message, this is the complete version

I have an Access database that I have exported to PostgreSQL via
ODBC, which has worked ok & the data is in PostgreSQL but some of
the column names were in mixed case e.g. AccountCode 

When I
look at the table definitions in pgadmin these are shown in quotes
e.g."AccountCode" and any queries made that reference these columns
require the quotes.

There are too many fields to issue alter table commands to rename in SQL so my question is , is it safe to use a query such as 

    select relfilenode from pg_class where relname='rates'

update  pg_attribute set attname=lower(attname) where attnum >0 and attrelid=nnnn ( from above query)

to rename the columns in the system catalogs or will this come back and bite me later?

Tony Cade