Complex Relationship Help Needed

[Bill C.]

I'm using FMPro 8 Advanced. My database has got a many-to-many between

tables A and B represented by a table AB -- so it's the normal

A --B

sort of pattern. In my application I have a form layout for A in which I

want to allow the user to add a new AB record; i.e., relate an additional B

to the specific A. I want to do this by way of a pick list, a new window

that opens and presents a portal containing B records that might be added.

(Ultimately I'd like this to be a multiple select list, but that's another

story.)

The trick however is to populate the portal ONLY with B's that aren't

already related to A via AB. I'm at a loss as to how to define the

corresponding relationship between A (or AB) and another instance of B that

will provide just those records out of B. One thing I've considered is using

a global field containing a multi-key constructed from the elements of AB

related to the specific A, but I need a != relation and (as I understand)

using a != with a multi-key would use "or" semantics and not produce the

list I'm looking for.

Any suggestions?

Thanks in advance,

Bill

[RalphL]

I have posted a sample file that demo's methods of doing this. I don't recall were so I am going to post it again.