Re: can I use two join in a single query ?

[Rick James]

Think of JOINs as being performed in the order listed. That's probably all you need to know, but here are some more details...

The query optimizer may reorder things, but not if it would change the result. (EXPLAIN SELECT ... show exactly what order will be used.)

The optimizer will remove "LEFT" in cases where it adds no constraint.

"INNER" and "OUTER" are ignored in MySQL.

STRAIGHT_JOIN prevents reordering by the optimizer -- this may help performance, but often bites you later.

Parentheses can be used for clarifying the semantics, but are rarely needed:
SELECT ... FROM a LEFT JOIN ( b JOIN c ON... ) ON ...
Try to avoid parens; they make it harder to read.