Database Reference
In-Depth Information
External Functions
If you've installed any plug-ins (“mini-programs” that add extra features to FileMaker), they
probably brought along some functions for their own use. FileMaker stores them in this cat-
Expressions
Expression is a fancy name for a subsection of a calculation—one or more fields, functions,
or constants, each connected with operators. When you made the first calculation in this
chapter (
Creating a Calculation
), you multiplied the contents of the field called Price Each by
the contents of the field called Quantity. That's a calculation, but it's also an example of an
expression
.
An expression always reduces to a single value when you combine its individual values ac-
cording to the operators. If you can't boil it down to a value, then it's not an expression.
That's an important point, because it means you can use expressions as function parameters
(
Functions
) just like any individual values—fields and constants. When used in a function,
these expressions are called
sub-expressions
.
Here are some examples of expressions:
The following is a simple expression, which reduces to the value 6.
3 + 3
Below is a more complex expression. It might turn a name into something like “Moss,
Maurice Q.”
Last Name & ", " & First Name & " " & Middle Initial & "."
The following calculation is a function
and
an expression, because it reduces down to a
single value:
Average ( L1 * W1 * H1 ; L2 * W2 * H2 ; L3 * W3 * H3 )
But if you look at just the stuff in parentheses, then you have this:
L1 * W1 * H1 ; L2 * W2 * H2 ; L3 * W3 * H3
That's
not
an expression because it doesn't reduce down to one value. It has three expres-
sions in all, each separated by a semicolon. Each expression reduces to a single value—three
values in all that become parameters passed to the
Average()
function.
You can put
any valid expression
in place of a parameter in a function. In the trade, that's
called
nesting
expressions. For example, you can rewrite the expression 3 + 3 like this:
