June 2017
Beginner to intermediate
368 pages
8h 31m
English
Content preview from Moodle 3.x Developer's Guide
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EXPLAIN a query
A MySQL database has a built-in query optimizer which, when you issue a SELECT query, will attempt to extract and present the required data as efficiently as possible. We can investigate the optimizer's query plan by prefixing the query with EXPLAIN. This function is easily accessible from the phpMyAdmin tools. For example, here's the query to determine the number of certificates issued, which has been explained by prefixing it with the EXPLAIN keyword:
In order to speed up the extraction of data from a table, a key is used. If the data is spread across a number of tables, or needs to be sorted in some way, MySQL may as well ...
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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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.