In this lesson, you’ll learn what subqueries are and how to use them.
SELECT statements are SQL queries. All the
SELECT statements you have seen thus far are simple queries: single statements retrieving data from individual database tables.
SQL also enables you to create subqueries: queries that are embedded into other queries. Why would you want to do this? The best way to understand this concept is to look at a couple examples.
The database tables used in all the lessons in this book are relational tables. (See ...