I think you'll need to tweak that one a bit:
If ( Get ( RecordNumber ) > 1 ; odometer - GetNthRecord ( Odometer ; Get ( RecordNumber ) - 1 ) ; Odometer )
And you may want to put some other value in place of Odometer--the value shown for the first record in your found set. You could use zero or just omit it to leave this field empty for the first entry.
This is excellent thank you very much everyone - i've eneded up making a very slight tweak to it and its now working exactly as I want it to.
If ( Get ( RecordNumber ) > 1 ; GetNthRecord ( Odometer ; Get ( RecordNumber ) + 1 ) ; ) - Odometer
What i think I might need now, is to learn the language used - would getting a visual basis's book help me to learn some of the language or does filemaker have some of its own proprietry languages?
If anyone knows a good book that would help me to learn some of the script language that might really help me rely less on this forum.
Thanks again all
This is not visual basic so it won't help you at all to get a gook on that topic.
There are several books in print. You can research them on Amazon. I can't recommend any one book as the best book will depend on your prior experience with relational database design. Plus I am not personnally familiar with the contents of each.
I just wondered if Visual Basis had any common language with FileMaker when it comes to calculation scripts in particular - i know that they are worlds apart but if there's a resource anywhere that can help me with this calcultion language i would love to get my hands on it.
Thanks anyway way Phil
There are numerous training resources available. Not only several book titles, but videos and other tutorials--even some on YouTube that you can investigate.
Forums like this are also a good resource, but the format makes them best suited for answering specific questions where the other resources are good for acquiring a general, "foundation" for your understanding of FileMaker and Relational Database Design.
And browsing through functions in FileMaker help often reveals new options/capabilities to the new developer.