7. Working with Groups of Rows
The queries you have seen so far in this book for the most part operate on one row at a time. However, SQL also includes a variety of keywords and functions that work on groups of rows—either an entire table or a subset of a table. In this chapter you will read about what you can do to and with grouped data.
Note: Many of the functions that you will be reading about in this chapter are often referred to as SQL's OLAP (Online Analytical Processing) functions.
Set Functions
The basic SQL set, or aggregate, functions (summarized in Table 7-1) compute a variety of measures based on values in a column in multiple rows. The result of using one of these set functions is a computed column that appears only in a result table. ...
Get SQL Clearly Explained, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
