Adding
ADABAS data as a result of update operations from various SAS procedures
might cause the interface view engine to decide whether to add a new
logical record to the
ADABAS file or modify an existing logical record, such as add an occurrence
to a periodic group. The purpose of the engine making this determination
is to reduce data redundancy.
The engine compares
values in the new observation to be added to values in the previous
observation. If the contents of the previous observation do not help
determine whether to add or modify, a new logical record is added.
However, some of the
new values might already reside in the
ADABAS file, so a new record is not necessary. This situation
occurs if a periodic group is included in a view descriptor, and the
new data (which does not reside in the
ADABAS file) occurs only in variables corresponding to data
fields that are part of that periodic group.
The interface view engine
can determine whether this situation exists. If not, a new logical
record can be added. If so, an existing record can be modified.
The optional BY key specification makes this possible. See
BY Key to Resolve Ambiguous Inserts.