3.2.6 JOIN Syntax:

table_references:

table_reference [, table_reference] ...

table_reference:

table_factor | join_table

table_factor:

tbl_name [[AS] alias] 
| table_subquery [AS] alias
| ( table_references )

join_table:

table_reference [INNER | CROSS] JOIN table_factor [join_condition]
| table_reference STRAIGHT_JOIN table_factor
| table_reference STRAIGHT_JOIN table_factor ON conditional_expr
| table_reference {LEFT|RIGHT} [OUTER] JOIN table_reference join_condition
| table_reference NATURAL [{LEFT|RIGHT} [OUTER]] JOIN table_factor

join_condition:

ON conditional_expr
| USING (column_list)