I'm having trouble with the following scenario:
drivers may have any of the 16 types of certificates, tasks may require any of the 16 types as well. What I need to do is build a query that will selectd all the tasks a certain driver can perform.
Example:
driver has these certificates: A,B,C,C1,C1E
so he can perform tasks that require any of these certs or any combination of certs (ie. only A, only B, both A and B, A and C1E, A,B and C1 etc).

I already have come up with a solution (which makes every possible combination), but it is very complicated and works well only with a smaller number of certificates, but with 16 (as it is the case) it requires more memory then it is available...

Any idea how to make a more efficient query?

Thanks for the time

You would have to go for a 'dynamic solution' where you are not guaranteed to hit the optimal solution.

A good example would be Dijkstra's shortest path finding algo.

Thanks, I'll look into it.