Hi,
I've read the PostgreSQL documentation on natural joins, but it only ever shows it being used once. Is it possible to use it more than once?
Say if I have the following 3 tables (this is a poor example by the way):
tbl_a
--------
a_id serial NOT NULL
location text
tbl_b
--------
b_id serial NOT NULL
language text
tbl_c
--------
c_id serial NOT NULL
a_id int NOT NULL
b_id int NOT NULL
I could write:
SELECT tbl_a.location, tbl_b.language
FROM tbl_c
INNER JOIN tbl_a ON tbl_c.a_id = tbl_a.a_id
INNER JOIN tbl_b ON tbl_c.b_id = tbl_b.b_id;
But could I also write:
SELECT tbl_a.location, tbl_b.language
FROM tbl_c
NATURAL INNER JOIN tbl_a
NATURAL INNER JOIN tbl_b
The confusion comes when 2 of those tables reference the 3rd table using the same column.
So are natural joins only allowed to join 2 tables? If not, how can it be used for more than 1 table has links to the other tables?
Thanks
Thom
