1 Reply Latest reply on Jul 1, 2013 11:17 PM by philmodjunk

    How do I set up a field so that a change in a calculation in the field does not affect previously...

    JohnBarks

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      How do I set up a field so that a change in a calculation in the field does not affect previously created records?

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           Hello Everyone,

             I have a few books on FileMaker development and I remember reading in one of them about how to set up a field so that a calculation change doesn't affect previously created records. For instance, I want to put all of my invoices into one database to make searching easier. But the way my database is set up now, if I change my hourly rate or the tax rates, it changes all of the past invoices as well. I cannot remember what to do to a field so that calculation changes do not affect already created invoices, only newly created ones. Can anyone help, please?

             Thanks,

             John B

        • 1. Re: How do I set up a field so that a change in a calculation in the field does not affect previously...
          philmodjunk

               The key is to use one auto-enter feature or another to copy the relevant data or calculation result into a field. Then Subsequent changes do not affect past records.

               Example 1: Put your hourly rate in a global field. Then define a rate field in your invoice or line item table (There's more than one way to do this depending on how you need your invoice to work) with an auto-enter calculation that copies the current value of the global rate field. THen set your calcualtions up to use ths value to compute costs. To change your rate, edit the global field and you won't see any existing invoices recalculate to use this new value, but a newly created record will use the new rate.

               Example 2: Put the value in a related table and use a looked up value setting to copy the value. THis is often used to copy unit price info from a table of products in an invoicing system. To change a price, you edit the price in the product table.