In Chapter 3, Making Use of Indexes, you learned about indexing, as well as about PostgreSQL's ability to run custom indexing code to speed up queries. In this chapter, you will learn about advanced SQL. Most of the people who read this book will have some experience in using SQL. However, experience has shown that the advanced features outlined in this book are not widely known, and therefore it makes sense to cover them in this context to help people to achieve their goals faster and more efficiently. There has been a long discussion on whether the database is just a simple data store or whether the business logic should be in the database or not. Maybe this chapter will shed some light and show how capable a modern relational database really is. SQL is not what it used to be back when SQL92 was around. Over the years, the language has grown and become more and more powerful.

This chapter is about modern SQL and its features. A variety of different and sophisticated SQL features are included and presented in detail. We will cover the following topics:

• Introducing grouping sets
• Using ordered sets
• Understanding hypothetical aggregates
• Utilizing windowing functions and analytics

By the end of this chapter, you will be able to understand and use advanced SQL.