For a commercial PHP library for building applications, have a look at
phpLens at
http://phplens.com/ This was developed by our company, and we have used
it develop some pretty big applications (100 company extranet for example).
There are other libraries available, some free. I like to search
You most certainly can write enterprise scale applications in
PHP/PostgreSQL. The web is littered with resources to make your life
easier. For me, PHPLIB (on sourceforge) has really saved my life. It's
getting a little long in the tooth and the docs are, erm, spotty. But
it is definitely
