I gather that you have two tables Customers---<MyMop (---< means one to many)
In customers, a calculation field can refer to MyMop::Sym 1 to refer to the first related record and Last ( MyMop::Sym 1 ) to refer to the latest related record--provided that the relationship does not specify a sort order or that specifies a sort order that keeps the rcords in the order that they were created.
That sounds like it should do the job - what's the syntax for specifying which record to refer to?
Presumably once that's in place, it's as simple as :
MYMOP::Symptom 1 Score [Last Related Record] - MYMOP::Symptom 1 Score [First Related Record]
Ah - after a bit of looking around, I now see that your answer did actually specify the syntax. I'd got the calculation as:
GetNthRecord ( MYMOP::Symptom 1 Score ; 1 ) - Last ( MYMOP::Symptom 1 Score )
I see that not specifying which record automatically retrieves the first - is there any value in specifying it explicitly as I have done above?
Thanks for your help.
I see no advantage to using getNthRecord here. If you had needed to refer to the 2nd, 3rd, etc record then it would be of use.