December 2003
Beginner
648 pages
14h 1m
English
Content preview from Sams Teach Yourself PHP, MySQL® and Apache All in One
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Optimizing Your Queries
Query optimization has a lot to do with the proper use of indexes. The EXPLAIN command will examine a given SELECT statement to see whether it's optimized the best that it can be, using indexes wherever possible. This is especially useful when looking at complex queries involving JOINs. The syntax for EXPLAIN is
EXPLAIN SELECT statement
The output of the EXPLAIN command is a table of information containing the following columns:
table— The name of the table.
type— The join type, of which there are several.
possible_keys— This column indicates which indexes MySQL could use to find the rows in this table. If the result is NULL, no indexes would help with this query. You should then take a look at your table structure ...
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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.