Re: adding missing FROM-clause

csgcsg39@hotmail.com ("C G") writes:

> Dear All,
>
> I have a simple join query
>
> SELECT c1 FROM t1
> INNER JOIN
> t2 ON t2.c2 = t1.c2 WHERE t3.c3= t2.c3;
>
> Which gives the expected result but I get the message
> NOTICE:  adding missing FROM-clause entry for table "t3"
>
> How do I get rid of this NOTICE, i.e. how should I construct my select
> query.
>

SELECT c1 FROM t1, t2, t3
   WHERE t2.c2 = t1.c2 AND t3.c3 = t2.c3;

or

SELECT c1 FROM t1
  INNER JOIN t2 ON t2.c2 = t1.c2
  INNER JOIN t3 ON T3.c3 = t2.c3;


The above can also be written as

SELECT c1 FROM t1
   JOIN t2 USING(c2)
   JOIN t3 USING(c3);

or even
SELECT c1 FROM t1
  NATURAL JOIN t2
  NATURAL JOIN t3;

This last might be problematic if t3 has a column named c1.


Question:

Is there any advantage to specifying USING() rather than ON?  I know
that if I do SELECT * from T1 JOIN t2 USING(col) then I only get 1
instance of col in the returned rows, but I'm wondering if there is
any advantage to the planner by specifying either USING() or ON?


--
Remove -42 for email