Secure/selective Data Access

Dear netters,

We are looking to build a SQL Server database that will be hooked up to
a Web server (WebLogic or a .NET).

The database will house data for multiple customers, and the
requirement is to have no customer see other customer data. Web server
will be responsible for authenticating users (ids and passwords will be
maintained there/possibly stored in the database, but will not be
actual database logins) -- and establishing pooled connections to the
database, using some sort of a proxy login.

Ideally, we do not want to have the database itself visible to "the
world", it should reside behind a firewall, and be accessible through
the Web server, which will do all authentication and routing.

We want to have either tables or views defined in such a way that:

1. Users can only see their own data and NEVER can see anybody else's.

2. Users' access to the database is logged (this includes updates as
well as queries).

3. We would like to provide some sort of a reporting mechanism -- where
users can form their own queries. So, something like a Crystal or an
Access front end, that users are typically familiar with... The problem
is that this requires users having direct access to the database (?),
and opens up tables (unless, there is a way to create parameterized
views that will always restrict access to a subset of records).

Any advice on how to best implement this is greatly appreciated.

Thank you in advance!