[Zope] Relational database & user permissions (select, add, update, delete)

[Jon Erickson]

I've run into a problem while developing a multi-user database
application using Postgresql and Zope with ZSQL methods.  I need
user\group based security for the database similar to...

User A can select from table FOO but cannot update, delete, or add
records to FOO.

User B can select, update and delete from FOO but cannot add records to
FOO.

... but most Database Adapters use a single, static user login for
database connections.  The single user login provides for easy db
connection configuration but doesn't help when you want to use a
databases built-in security.  I don't really want to program this logic
in python when Postgresql already has said features.

Does anyone have experience implementing user-level database security in
a Zope app?  If so, could you reply with some suggestions or examples
please.

Thanks,

Jon Erickson