IBM 15 Manual De Usuario
115
Building CLEM Expressions
Calculating Time Passed
You can easily calculate the time passed from a baseline date using a family of functions similar to
the following one. This function returns the time in months from the baseline date to the date
represented by the date string
the following one. This function returns the time in months from the baseline date to the date
represented by the date string
DATE as a real number. This is an approximate figure, based on a
month of 30.0 days.
date_in_months(Date)
Comparing Date/Time Values
Values of date/time fields can be compared across records using functions similar to the following
one. This function returns a value of true if the date string
one. This function returns a value of true if the date string
DATE1 represents a date prior to that
represented by the date string
DATE2. Otherwise, this function returns a value of 0.
date_before(Date1, Date2)
Calculating Differences
You can also calculate the difference between two times and two dates using functions, such as:
date_weeks_difference(Date1, Date2)
This function returns the time in weeks from the date represented by the date string
DATE1 to the
date represented by the date string
DATE2 as a real number. This is based on a week of 7.0 days. If
DATE2 is prior to DATE1, this function returns a negative number.
Today’s Date
The current date can be added to the data set using the function
@TODAY. Today’s date is added as
a string to the specified field or new field using the date format selected in the stream properties
dialog box. For more information, see the topic
dialog box. For more information, see the topic
in Chapter 8 on p. 146.
Summarizing Multiple Fields
The CLEM language includes a number of functions that return summary statistics across
multiple fields. These functions may be particularly useful in analyzing survey data, where
multiple responses to a question may be stored in multiple fields. For more information, see the
topic
multiple fields. These functions may be particularly useful in analyzing survey data, where
multiple responses to a question may be stored in multiple fields. For more information, see the
topic
on p. 117.
Comparison Functions
You can compare values across multiple fields using the min_n and max_n functions—for example:
max_n(['card1fee' 'card2fee''card3fee''card4fee'])