The SQL Workshop

10. Aggregate Functions

Overview

In this chapter, we'll use SQL aggregate functions and solve problems with them. By the end of this chapter, you'll be able to use SQL aggregate functions and the GROUP BY clause, implement the SQL HAVING clause, explain the differences between the HAVING and WHERE clauses, use the SQL OVER and PARTITION BY clauses, and implement the RANK and DENSE_RANK functions.

Introduction

In the previous chapters, we saw that the WHERE clause can be used to filter SQL query result sets in an efficient, almost intuitive way. For example, say we want to identify the total number of executives in a department, or we want the total number of dependents who are covered by a medical claim. In such cases, more than the details, ...