From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Julian Scarfe <jscarfe(at)callnetuk(dot)com> |
Cc: | PostgreSQL-general <pgsql-general(at)postgreSQL(dot)org> |
Subject: | Re: [GENERAL] Simulating an outer join |
Date: | 2000-01-12 23:45:52 |
Message-ID: | 200001122345.SAA20709@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-general |
> > UNION ALL
> > SELECT table1.key, NULL
> > FROM table1 WHERE NOT EXISTS
> > (SELECT table2.key FROM table2 WHERE table1.key = table2.key);
>
> FWIW, that's exactly Joe Celko's SQL-89 workaround for OUTER JOINs in 'SQL for
> Smarties'. Well in fact he uses (SELECT * FROM table2 WHERE table1.key =
> table2.key) as the subquery, but I presume that's an insignificant difference.
I am just writing the EXISTS section from my book. I don't think it
matters what fields are returned from an EXISTS subquery. If I am
wrong, someone please let me know.
--
Bruce Momjian | http://www.op.net/~candle
maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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