> Is it possible for a MySQL connection to request a downgrade in
> privileges? What I'd like to be able to do is create one database
> user account for a database application with read and write
> privileges to the tables, but if an application user logs in who
> only has read access, then to downgrade the permission's on the SQL
> server for the database user to select only for that connection.
I don't know of a way to do exactly what you describe, but you can get
the same effects by creating two accounts, one with only SELECT
privileges and one with whatever write privileges you need. Then
you application can simply decide which account to authenticate with.
> I want to be able to give an added level of assurance that the user
> will not be able to write to the database even if the application
> controls are circumvented.
That sounds like an excellent design decision.