You should be
familiar with the use of the DATA step to merge data sets. DATA step
match-merges and PROC SQL joins can produce the same results. However,
there are important differences between these two techniques. For
example, a join does not require that you sort the data first; a DATA
step match-merge requires that the data be sorted.
Compare the use of SQL
joins and DATA step match-merges in the following situations:
when all of the values of the selected
variable (column) match
when only some of the values of
the selected variable (column) match.