SAS Certification Prep Guide, 4th Edition

Subsetting Data By Using Correlated Subqueries

Overview

Correlated subqueries cannot be evaluated independently, but depend on the values passed to them by the outer query for their results. Correlated subqueries are evaluated for each row in the outer query and therefore tend to require more processing time than noncorrelated subqueries.

Note: Usually, a PROC SQL join is a more efficient alternative to a correlated subquery. You should already be familiar with basic PROC SQL joins.

Example

Consider an example of a PROC SQL query that contains a correlated subquery. The following query displays the names of all navigators who are also managers. The WHERE clause in the subquery lists the column Staffmaster.EmpID. The outer query must pass ...