Database Reference
In-Depth Information
Shadow Tables
If you switch to the Tables tab in the Manage Database window, you may see something un-
expected. FileMaker includes every SQL table you've added to your graph in the Tables list
(in stark contrast to tables from other FileMaker databases, which never show in the Tables
tab).
NOTE
No matter how many
table occurrences
you create for a particular SQL table, the underlying table is
listed only once. Also, SQL tables are always shown in italic so they're easy to spot.
The italicized entry in the Tables tab is called a
shadow table
. In other words, it isn't the
table. Rather, it's a representation of the real table. It reflects information about the real table
and even lets you add a little FileMaker magic to an otherwise bare bit of computer science.
If you double-click the table (or switch to the Fields tab and then select the table from the
Table pop-up menu), you'll see the fields (sometimes called
columns
by non-FileMaker data-
base folks) from the SQL table listed in italic as well. You can do certain things to these it-
alicized fields:
▪ You can add a field comment if you want.
▪ You can click Options and set auto-enter and validation options for the field. Remember,
though, that the rules you set here apply only when you add or edit records
in FileMaker
.
Other systems that interact with the database are restricted only by settings in the SQL
database.
▪ You can delete a field. You're not actually deleting the field from the SQL table. Rather,
deleting a field tells FileMaker you simply don't want to see that field in FileMaker any-
more. (You can always get it back later by clicking the Sync button, as explained below.)
However, you can't rename a field or change its type. That sort of thing is controlled on the
SQL database side of things.
SQL databases tend to be more restrictive about acceptable values than FileMaker itself. For
instance, a text field in a SQL database usually has a maximum size that's relatively small,
compared with FileMaker's 2 GB field limit. If you select a field, click the Options button
and then visit the Validation tab, where you might see that the “Maximum number of charac-
ters” option is turned on, and you can't turn it off. Right by the checkbox, FileMaker also
shows how many characters the field can hold.
