[Exim] Multiple Databases?

I'm currently running the 3.3x series of exim, and I'm trying to get it to
query multiple databases for authentication purposes. I know i can list
multiple databases in the mysql_server setting, but that's just for failover
purposes.
I've also tried using "use <dbname>;" before the select in a query, but it
seems mysql complained maddly about malformed queries :(

Has anyone got this working, or can anyone point me in the right direction.

(is now on his third job and third time of using exim in a row :))

If Anyone can help, I'd greatly appreciate it,

Cheers,
Colin Morey,
System Administrator