A summary field can be used but only if you can do a find and sort that groups your records in the join table by the value of _fk_TopicID.
IF you need this same count in other contexts than that, there are other approaches--such as a self join to a new occurrence of the join table that matches records by this field or, if you have FMP 12, there are ways to use Execute SQL to produce such a count.
What I want to do is have a field that constantly shows the result that I want without doing a find. I thought far enough to know that a find or a summary list report could provide the answers. But, I am wanting a field that I can place into an existing portal along side each respective _fk_TopicId so that I can view the count progression as time and compositions evolve.
So, that said, I have FM Pro 10 Adv. Can you give me some help on a self join or something that can get the process working? OR simply tell me that the effort is to great to mess around with. I would like to learn a way though rather than trash the thought.
Seems like a process that many people could use in many different ways. Then again, maybe not. Seems like it could be something for FM to develop into a more user friendly approach.
Incidentally, PhilModJunk, your input and guidance has provided me great success in my last post of having one portal fill another portal with data. It is all up and running very nicely. Took some time; but, got 'er done. Thanks a lot for your help.
I think I recall that the join table was called something link compos_topic.
compos_topic::_fk_TopicID = compos_TopicSameTopic::_fk_TopicID
compos_TopicSameTopic would be a new occurrence of compos_Topic.
Then, on a layout or portal based on compos_Topic, you can use Count ( compos_TopicSameTopic::_fk_TopicID ) defined to evaluate from the context of compos_Topic to show the current count of join table records with the same topic ID.
HOT DIGGITY DOG!!!!
I got it to work the first time through. Can't believe I'm comin' back on this FM stuff.
Thanks a big bunch!! Now I'll work on getting the results to display on the given layout where I want them to.