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 readers of this book will have some experience of 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 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.

This chapter is about modern SQL and its features. A variety of different and sophisticated SQL features are included and presented in detail. The topics covered are as follows:

• Grouping sets
• Ordered sets
• Hypothetical aggregates
• Windowing functions and analytics

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