User's Manual

110
Chapter 7
Frequently, special functions are used in combination, which is a commonly used method of
flagging blan k
s in mor e than one field at a time.
@BLANK(@FIELD)-> T
Additional examples a r e discussed throughout the CLEM d ocumentation. For more information,
see the topic CLEM Reference Overview in Chapter 8 on p. 127.
Values and Data Types
CLEM expressions are sim ilar to formulas constructed from values, field names, ope r ators, and
functions. The si mplest valid CLEM e xpression is a value or a field name. Examples of valid
values are:
3
1.79
'banana'
Examples of field names are:
Product_ID
'$P-NextField'
where Product is the name of a field from a market basket data set, ’$P-NextField’ is the name
of a parameter, and the value of the expression is the value of the named field. Typically, field
names start w ith a letter and may also contain digits and underscores (_). You can use names that
do not follow these rules if you place the name within quotation marks. C LEM values can be
any of the following :
 Strings—for example, "c1", "Type 2", "a piece of free text"
 Intege r s—for example, 12, 0, –189
 Real numbers —for example, 12.34, 0.0, –0.0045
 Date/tim e fields—for example, 05/12/2002, 12/05/2002, 12/05/02
It is also possible to use the following elements:
 Character codes— f or e xample, `a` or 3
 Lists of items—for example, [1 2 3], ['Type 1' 'Type 2']
Charac ter codes an d lists do not usually occu r as field values. Typically, they are used as
arguments of CLEM functions.
Quoting Rules
Although the software is flexible when determining the fields, values, parameters, and strings
used in a CLEM e xpress ion, the following general rules provide a list of “best practices” to use
when creating expressions:
 Strings—Always use double quotes when writing strings ("T
ype 2" or "value"). Single quotes
can be used ins tead but at th e risk of confusion with quoted fields.