ASA Getting Started
Selecting Data Using Subqueries
A relational database allows you to store related data in more than one table. The chapter Selecting Data from Multiple Tables outlines one way of extracting data from related tables. A second method involves subqueries—queries that appear in another query's WHERE clause or HAVING clause. Subqueries make some queries easier to write than joins, and there are queries that cannot be written without using subqueries.