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Keeping It Simple - MySQL

Left join. Right join. Inner join. If you've ever wondered what all this jargon means, it's time to find out. Welcome to the wild, the wacky, the insanely cool world of SQL joins.

TABLE OF CONTENTS:
  1. Understanding SQL Joins
  2. Meeting The Family
  3. Keeping It Simple
  4. Crossed Wires
  5. Finding Common Ground
  6. One Step Left...
  7. ...Two Steps Right
  8. The Bookworm Turns
  9. Up A Tree
  10. A Long Goodbye
By: The Disenchanted Developer, (c) Melonfire
Rating: starstarstarstarstar / 247
August 20, 2002

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We'll start with something simple. The general format for a SELECT statement is:

SELECT <column list> FROM <table list> WHERE <condition list>;
Here's an example of how it can be used - the following SQL query retrieves all the records in table "a".

SELECT * FROM a;
Here's the output:

+----+------+ | a1 | a2 | +----+------+ | 10 | u | | 20 | v | | 30 | w | | 40 | x | | 50 | y | | 60 | z | +----+------+
I can filter out some of these records by adding a WHERE clause:

SELECT * FROM a WHERE a1 > 20;
This returns

+----+------+ | a1 | a2 | +----+------+ | 30 | w | | 40 | x | | 50 | y | | 60 | z | +----+------+
And I can even restrict the number of columns shown, by specifying a list of column names instead of the all-purpose asterisk:

SELECT a2 FROM a WHERE a1 > 20;
Which gives me:

+------+ | a2 | +------+ | w | | x | | y | | z | +------+


 
 
>>> More MySQL Articles          >>> More By The Disenchanted Developer, (c) Melonfire
 

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