The MERGE statement and the UPDATE statement both match
observations from two SAS data sets. However, the two statements differ
significantly. It is important to distinguish between the two processes
and to choose the one that is appropriate for your application.
The most straightforward
differences are as follows:
The UPDATE statement uses only
two data sets. The number of data sets that the MERGE statement can
use is limited only by machine-dependent factors such as memory and
A BY statement must accompany an
UPDATE statement. The MERGE statement performs a one-to-one merge
if no BY statement follows it.