SQL in 24 Hours, Sams Teach Yourself, 7th Edition

Hour 17

Summarizing Data Results from a Query

What You’ll Learn in This Hour:

• ▶   Defining functions

• ▶   Using aggregate functions

• ▶   Summarizing data with aggregate functions

• ▶   Getting results from functions

• ▶   Understanding why you want to group data

• ▶   Grouping results with the GROUP BY clause

• ▶   Using group value functions

• ▶   Understanding group functions

• ▶   Grouping by columns

• ▶   Deciding between GROUP BY and ORDER BY

• ▶   Reducing groups with the HAVING clause

In this hour, you learn about the aggregate functions of SQL. You can perform a variety of useful functions with aggregate functions, such as getting the highest total of a sale or counting the number of orders processed on a given day. The real power of aggregate functions ...