Here are some tips that
can help you specify ID variables effectively in aggregations:
-
A useful technique
for specifying ID variables is to choose columns that are based on
or determined by the value of a column that is already in the class
list. An example of this is to choose DATE or DATETIME-based columns
that are less granular than the aging column.
For example, consider
the case where you have an aggregation that is aged according to the
DAYDATE column, which records daily date values. The columns WEEKDATE
and MONTHDATE are excellent candidates for use as ID columns because
they are (essentially) determined by the value of DAYDATE. Thus,
when creating reports, you can easily determine the days that belong
with a particular week.
The same is true for
other types of date or datetime-based columns that the user might
create, such as a column that represents the calendar quarter or accounting
period.
-
ranking of DATE/DATETIME-based
class or ID columns
This tip is a corollary
to choosing ID columns based on date, or datetime values. If you have
such columns in the class or ID list, then requesting a descending
rank on such a column simplifies the report task of reporting on the
"last N time periods" (such as the last three weeks). For example,
if WEEKDATE is an ID column in an aggregation that has DAYDATE in
the class list, then a descending rank on WEEKDATE facilitates reporting
on the last three weeks of daily values. The report simply needs to
filter where WeekDateRankDescending >= 3. (All the supplied aggregations
and information maps make use of this feature.)