Data Transformation Engine Functions and Expressions Reference Guide

Chapter 1 - Expressions and Evaluations Using Functions in Expressions

Functions and Expressions Reference Guide

Operands

Operands are the arguments for an operator. For example, in the expression a +

b, the + is the operator symbol, and a and b are the operands.

An operand can be any of the following:

♦ a literal

♦ a data object name

♦ a function

♦ another operator

Using Functions in Expressions

Functions perform a particular action on its input arguments. A function is written

like this:

FUNCTION (argument1, argument2, ... argumentn)

The arguments of the function appear inside the parentheses, separated by

commas. A function may require a fixed number of arguments or may allow a

varying number of arguments. You can use functions anywhere in an expression.

Function Arguments

Input arguments themselves can be expressions. Some functions limit the type of

expression that can be used as an input argument. Chapter 2 - Using Functions

explains the notation used for different expressions.

The type of expression that can be used as an input argument to a particular

function is specified as part of the function definitions in Chapter 3 - Function

Reference. The syntax specification also tells you the number of data objects can

be used for one function evaluation.

There is always one output argument for a function. The specification of the

output argument tells you: 1) the type of the result produced by a function and

2) the number of objects that can be produced when the function evaluates once.

You need to know the type of the output argument because functions can be used

as other arguments. The result of a function can also be used to directly produce

an output data object contained in an output destination.

When the Map Designer analyzes the interfaces of expressions in rules during the

build process, it ensures that the output argument of a function matches the input