Summary

In this chapter, you saw how you can use SQL to summarize data from multiple rows. To start with, the rows that were summarized were selected simply by a WHERE clause. To make summarization techniques more powerful, you can also look at groups of data, which you did in the second half of the chapter.

To be specific, you learned about the following:

• Using the COUNT function

• Using the SUM function

• Using the AVG function

• Using the MAX and MIN functions

• Grouping data using the GROUP BY clause

• Using the HAVING clause with data groups

• Limiting the number of rows returned, using Top-N queries

You even took a sneaky look at the more advanced topic of analytic functions.

This chapter used calculations and functions in many of its examples. In the next chapter, you'll learn about this subject in more detail.