INSERT and UPDATE page examples?

I need to construct a set of admin pages for a website so internal users can
INSERT and UPDATE data for a group of related tables.  I dont want to
re-invent the wheel on this and due to nested foreign key constraints, it's
not so straightforward.


Here's my example:

Project
---------
proj_id   pkey
title     varchar

Employees
-----------
empl_id   pkey
dept_id   fkey
name        varchar

ProjEmployees (many employees on a project)
--------------
proj_id   pkey/fkey
empl_id   pkey/fkey

Department
-----------
dept_id   pkey
name      varchar


Creating a COMPLETE PROJECT involves populating all of these tables but
users dont think ahead and understand the dependencies. A person adding
Employees to a Project will have to search for that Employee and then add
them. Sometimes they will suddenly realize that they need to create (insert)
a new Employee before they can add them to a Project (add to ProjEmployees)
and maybe then have to create (insert) a new Department, and so on...

Are there some pre-existing examples for how to go about this in PHP/Psql?


Thanks,

-Aaron