What's the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN and FULL JOIN? 

Answer:

Reading this original article on The Code Project will help you a lot: Visual Representation of SQL Joins.

Also check this post: SQL SERVER – Better Performance – LEFT JOIN or NOT IN?.

Find original one at: Difference between JOIN and OUTER JOIN in MySQL.

http://stackoverflow.com/questions/5706437/whats-the-difference-between-inner-join-left-join-right-join-and-full-join