SAS Enterprise Guide supports the idea of subqueries, a concept familiar to SQL programmers. With a subquery (sometimes called "subselect" or "inner query"), you can express the entire operation in one SQL step. That's one trip to the database, and only one set of results brought back to SAS.  

You accomplish this by using Query Template to define the inner query, then combine it with an expression of the outer query.  For more information, read Building an SQL subquery in SAS Enterprise Guide.

Thanks to @MichaelB_SAS for the SAS Global Forum paper that supports this tip