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Appendix F. IBM Cognos Transformer Expression Editor
The Cognos Transformer expression editor is not the same expression editor as the
one used in Framework Manager or the Web studios.
The expression editor can be invoked from a number of places within Cognos
Transformer. The functionality varies depending upon whether you are creating a
calculated dimension, calculated category, calculated column or calculated measure.
An expression is any combination of operators, constants, functions, and other
components that evaluates to a single value. You build expressions to create
calculations. A calculation is an expression that you use to create a new value from
existing values contained within a data item.
An expression can include
v
functions, such as Day and Months-Between
The Functions folder in the Available Components box contains functions
provided by Cognos Transformer. These are pre-defined calculations, such as
string, numeric, and date calculations, that are designed to operate on various
data types.
v
constants, such as numbers, strings, and date
Constants are typed directly into the expression once the type of value is
determined.
The expression editor is context-sensitive, so it presents only options that are
relevant at each stage of expression building.
v
operators, such as +
Operators specify what happens to the values on either side of the operator.
There are four types:
– mathematical operators perform mathematical operations on two parts of an
expression (for example: +, -, *, /, ^)
– string operators concatenate two character strings (+)
– logical operators define a relationship between two parts of an expression (for
example: and, not, or)
– comparison operators filter data by comparing one or more values that you
enter against the values in the expression (for example: like, =)
Note: Cognos Transformer supports mathematical operators and string
concatenate operators. It also supports logical operators and comparison
operators, but only in an if-then-else conditional construct.
v
the if-then-else conditional construct
You can build expressions in four functional areas in Cognos Transformer:
v
calculated columns in a data source
v
calculated categories
v
calculated measures
v
calculations that apply to a set of categories or levels within a dimension
The components that are available to build an expression depend on:
v
the type of calculation
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