In my ASP.NET MVC application I allow users to log in. Each user is associated with a company. Company ID and company data is not part of the Users table in the database. User and Company are connected through a related table (one to many relationship). Company ID is not part of the Users table as a foreign key because the design of the Users table did not predict that and we are not allowed to change it.
When user logs on we want to take the company ID for this user and store it somewhere. We would use this ID later for querying and other kinds of filtering by company because the content is stored per company.
Where should I store the company ID setting to make it persistant over many web request?