Help with a tally calculation

[oilcan]

So I'm trying to create a calculation field that will be based on a self relationship. The self relationship is to define all records with the same value in _kf_Cell_Line_ID. The idea is the tally calculation, which I currently call Cell_Line_Rep_Tally, should function in such a fashion in that it will increment by 1 for each new record created that uses the same foreign key _kf_Cell_Line_ID. Obviously it should not change in extant records, only update when the record is newly created.

The notion behind this is simple. In our lab, we may use a particular cell line to produce a certain protein multiple times. We call each growth of a particular cell line a batch. I'm basically trying to create a simple, uniquely identifying 'batch number' for lab techs that would be represented by '(cell line number).(batch number)' where batch number equals the tally of the number of times this particular cell line has been used to grow a batch. i.e. the eleventh batch grown of cell line 4 would be represented as 4.11

I'm hoping this is making some sort of sense. Anyway, I'm not having much luck getting this tally to function properly, as I am quite novice to filemaker, and it's been over 14 years since I used any sort of programming logic I was hoping someone might be able to offer me a hint as to how to accomplish this, if my approach with a self relationship and a calculation is even the best way to approach this, etc.

Thanks.

[mr_vodka]

Perhaps this thread could help you...

Internal Customer Serial Numbering

[oilcan]

thanks, that's certainly the type of functionality I'm looking to create. Much appreciated.