Considering the fact  I'm not growing any younger and start forgetting things, here's a very short hands on self reminder article about mysql join types.

JOIN

SELECT stuff FROM a JOIN b ON a.x = b.y

returns only records from a that have correspondent in b

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LEFT JOIN

SELECT stuff FROM a LEFT JOIN b ON a.x = b.y

returns all records from a, no matter if they have correspondent in b or not

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RIGHT JOIN

SELECT stuff FROM a RIGHT JOIN b ON a.x = b.y

returns all records from b, no matter if they have correspondent in a or not

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INNER JOIN

equivalent to simple JOIN

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LEFT OUTER JOIN
RIGTH OUTER JOIN


OUTER is needed for ODBC compatibility. it doesn't do anything.