PROC SQL: Beyond the Basics Using SAS®

7.1. Introduction

In previous chapters, our discussion of queries was confined to a single table referenced with a SELECT statement. The real strength of the relational approach is the ability it gives you to construct queries that refer to several tables or even to other queries. These types of queries are referred to as complex queries. PROC SQL provides a way to construct complex queries by enabling you to join two or more tables, build queries that control other queries through a process known as nesting, and combine output as a single table from multiple queries.