Field Options - FileMaker Pro 13: The Missing Manual - page 298

can sit down at another user's computer and enter some information; you really only know
which computer the information came from, not which person. A more reliable method of
tracking the “who” part of metadata is to create database Account Names instead. To learn
how to set up and manage accounts, see Managing Accounts .
Modification Values
It's useful to know when a record was created , but it's even more useful to know when it was
last changed . That way, you can quickly find everything that temp you hired last week
messed up, or see how stale the info you have on your best customer is. But “change” is such
a pedestrian word, hardly suited to the highbrow world of database development, so
FileMaker calls it modification instead. Making modification info available in your database
is a familiar exercise:
Make a new Timestamp field called modificationTimestamp. Then in the field's Auto-Enter
options, turn on the Modification checkbox and then, from the pop-up menu, choose
“Timestamp (Date and Time).”
You might hesitate to turn on the “Prohibit modification of value during data entry” option
this time. After all, you want this field to change every time you enter data in a record. But
don't fret. This checkbox keeps you from typing into the field, but FileMaker can still update
its value for you. So by all means, turn the “Prohibit modification” checkbox on. Manually
changing this field is just as much a problem as changing the Creation Date field.
NOTE
In Chapter 12 , which covers scripting, you'll discover other ways to change a field that don't in-
volve data entry. The “Prohibit modification” option applies only to the process of a human being
interacting with a field in Browse mode.
Serial Number
Back in Chapter 1 , you learned that record numbers (as viewed in the Current Record Indic-
ator) can change as records get deleted or sorted. Then on Understanding the Elements of a
Relationship , you saw that when you want to assign a unique number to your record, you use
the “Serial number” auto-enter option. Here's more detail on how that works: A serial num-
ber is a field whose value goes up for each new record. Typically, it goes up by a count of
one, so the first record might be 1, 1001, or INV0001. In the second record you create, the
serial number field would be 2, 1002, or INV0002. The numbers don't have to go up by one
with each new record—you can provide any “increment by” value you want. But the value
always goes up by some fixed amount.