Which of the three clauses are equivalent please:
(1) FROM a LEFT JOIN b ON x=y LEFT JOIN c ON xx = yy
(2) FROM (a LEFT JOIN b ON x=y) LEFT JOIN c ON xx = yy
(3) FROM a LEFT JOIN (b LEFT JOIN c ON xx = yy) ON x=y
?
Do SQL standards say anything about JOIN associativity?
Guy Hengel [angelIII / a3]

JOIN is associative, so the order/brackets would not matter

now, LEFT JOIN is a different matter, as:
a LEFT JOIN b
will not give the same results as
b LEFT JOIN a

so, LEFT JOIN is not associative as such

however, your refer to the the bracketing for LEFT JOINs, which is associative.

Sorry angellll, it looks like you mean commutativity (a JOIN b) = (b JOIN a), and I am talking about associativity, i.e. is
((a join b) join c ) the same as (a join (b join c))?

So once again:
Is (1) in my question equivalent to (2) and / or (3)?

yes, sorry :) math courses are some time ago ...

i.e. is ((a join b) join c ) the same as (a join (b join c))?
yes, JOIN is associative

and yes, (1) is the same as (2) and (3).