-------------- New JOIN types -------------- Author: Adriano dos Santos Fernandes <adrianosf@uol.com.br> Format: <named columns join> ::= <table reference> <join type> JOIN <table reference> USING ( <column list> ) <natural join> ::= <table reference> NATURAL <join type> JOIN <table primary> Notes: Named columns join: 1) All columns specified in <column list> should exist in the tables of both sides. 2) An equi-join (<left table>.<column> = <right table>.<column>) is automatically created for all columns (ANDed). 3) The USING columns can be accessed without qualifier, and in this case, result of it is COALESCE(<left table>.<column>, <right table>.<column>). 4) In "SELECT *", USING columns are expanded once, using the above rule. Natural join: 1) A "named columns join" is automatically created with all columns common to the left and right tables. 2) If the is no common column, a CROSS JOIN is created. Examples: 1) select * from employee join department using (dept_no); 2) select * from employee_project natural join employee natural join project;