Database Reference
In-Depth Information
In the Field Options dialog box, once you turn on the “Serial number” checkbox, you can
specify the “next value,” which is the value FileMaker uses for the next record that you cre-
ate (usually, the starting value). The “increment by” value tells FileMaker how much to add
with each new record.
You can specify non-numerical values for “next value” if you want. For example, if your
field is a text field, you can put INV00001 in the “next value” box. Your first record would
then get INV00001, followed by INV00002 and INV00003.
The Generate radio buttons under “Serial number” control
when
the serial number is as-
signed. If you select “On creation,” then as soon as you create a record, FileMaker puts the
serial number in the field. If you decide you don't want the record, even if you delete it right
away, that serial number value has been
used up
, and the next record you make has a new
serial number. In almost every case, losing a serial number poses no problem at all, and it's
convenient to have the serial number value available before you commit the record because
serial numbers are so often used as key fields when you're creating relationships.
If you select “On commit” instead, then the serial number doesn't show up in the field until
you exit the record. In other words, you can delete this new record without
committing
, and
you haven't used up a serial number. Still, unless you have a good reason (like a stringent
government regulation that requires you to record every single transaction with a string of
unbroken serial numbers), you should use the “On creation” option. See the box below for
more on committing records.
UP TO SPEED: EMBRACING COMMITMENT
The word
commit
refers to a semi-technical database concept. When you create a new record, you
haven't actually added a record to the table yet. Instead, you get a blank record on the screen, and
the information you enter is stored in a temporary working area in your computer's memory. When
you exit the record, the information in that working area is
committed
—or written—to the database.
When you edit a record, the same principle holds: As soon as you enter the record, it's copied to the
working area. While you edit it, you're actually editing this copy. When you exit the record,
FileMaker puts your edited copy back in the table. In general, think of
committing
a record as the
same thing as
exiting
a record. When you exit the record, you commit it.
You use serial numbers most often when you create relationships between tables. Serial num-
bers also come in handy when the items in your database don't have a convenient name. In a
database of invoices, it can be tough to talk about one particular invoice. (“You know, that
one we sent last Thursday. No, not that one, the
other
one.”) People generally use serial num-
bers to clarify things.
