First of all apologies for the confused-sounding title of this thread; I sat for a while trying to put my problem into a few words and that's the best I could come up with.
Here's my problem in a few more words - I have a chain of related tables, one linked to the next via a one-to-many relationship. Together they define how users of a particular system connect to remote computers, by defining a) a list of personnel, b) a list of accounts held by personnel, c) a list of jump machines to which each account has access, d) a list of remote systems to which each jump machine has access. For each remote system I want to present in a form (via a query) a list of all personnel who have access to it. Person X has access to System Y if he/she has an account to a jump machine which has access to that system. There are actually two more steps in my database but the above is a simplified model of the problem.
(NB a jump machine is an intermediate machine to which a person needs to gain access in order to connect onwards to the final remote system).
I have been grappling with various SELECT queries using different sorts of JOINs, but all I've managed to achieve is a list of all users. I have not been able to specify the intervening criteria which determine if a record in the Personnel table should be included or not.
If anyone can a) understand what I'm trying to describe above and b) offer any pointers, I would be very grateful.