Re: adding missing FROM-clause

csgcsg39(at)hotmail(dot)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?

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