April 2007
Intermediate to advanced
1032 pages
19h 28m
English
book
SQL for MySQL Developers: A Comprehensive Tutorial and Reference
by Rick F. van der Lans, Diane Cools
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Chapter 10. SELECT Statement: The GROUP BY Clause
10.1 Introduction
The GROUP BY clause groups rows on the basis of similarities among them. For example, we could group all the rows in the PLAYERS table on the basis of the place of residence. The result would be one group of players per town. From there, we could query the number of players in each group. The final result answers the question, how many players live in each town? Other examples are: How many matches has each team played, and how much has each player incurred in penalties? In short, the GROUP BY clause is frequently used to formulate questions based on the word per.
By adding aggregation functions, such as COUNT and SUM, to a select block with the use of a GROUP BY clause, data ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.