Building on Subqueries, Common Table Expressions, and Unions
The most common way to use more than one table in a query is by joining them, which you learned about in Chapter 5. This chapter will explain several other ways to combine tables in a query. Subqueries and common table expressions (CTE) allow you to isolate the logic of complex queries. Union queries allow you to combine the results of two independent queries into one result set. The first thing you will learn in this chapter is how to substitute a query for a hard-coded IN list.
This section demonstrates using subqueries in the WHERE clause. A subquery ...