SAS Certification Prep Guide, 4th Edition

Comparing SQL Joins and DATA Step Match-Merges

Overview

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.

When All of the Values Match

When all of the values of the BY variable match, you can use a PROC SQL inner join to produce ...