Re: [HACKERS] Outer joins

From: Kaare Rasmussen <kar(at)webline(dot)dk>
To: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] Outer joins
Date: 1999-06-05 06:58:05
Message-ID: 199906050658.IAA17164@bohr.webline.dk
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> Left outer joins will take the left-side table and null-fill entries
> which do not have a corresponding match on the right-side table. If
> your example is trying to get an output row for at least every input
> row from t1, then perhaps the query would be
>
> select * from t1 left join t2 using (x)
> left join t3 using (x)
> left join t4 using (x);
>
> But since I haven't implemented it yet I don't have much experience
> with the outer join syntax...

You miss at least two points: The keyword OUTER and the column name
from t1. As I know, LEFT is the default, so it could be omitted.

Maybe
SELECT * FROM t1 USING (X) OUTER JOIN t2 USING (Y)
OUTER JOIN t3 USING (Z)
OUTER JOIN t4 using (t);

It should be possible to boil it down to
SELECT * FROM t1 USING (X) OUTER JOIN t2 USING (Y), t3 USING (Z), t4 using (t);

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