Oracle SQL By Example

Chapter 6. Aggregate Functions, GROUP BY, and HAVING Clauses

In the last two chapters, you learned about character functions, number functions, date functions, and miscellaneous functions—all single-row functions. In this chapter, you will learn about aggregate functions, which work on groups of rows. The most commonly used aggregate functions are discussed. Aggregate functions allow you to generate summary data for a group of rows to obtain totals, averages, counts, minimum values, and maximum values. In Chapter 17, “Exploring Data Warehousing Features,” you will learn about advanced SQL aggregation topics involving the ROLLUP ...