Re: request for sql3 compliance for the update command

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Hannu Krosing <hannu(at)tm(dot)ee>, Dave Cramer <dave(at)fastcrypt(dot)com>, scott(dot)marlowe(at)ihs(dot)com, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: request for sql3 compliance for the update command
Date: 2003-03-19 14:46:00
Message-ID: 6708.1048085160@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> I wasn't sure it made logical sense to allow correlated subqueries in
> FROM because the FROM is processed before the WHERE.

It doesn't; in fact it violates the whole semantic model of SQL,
as far as I can see. Sub-selects in FROM are (in principle)
evaluated separately and then joined. They can't have cross-references.

I think there is some weird construct in SQL99 that alters this behavior,
though.

regards, tom lane

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Hannu Krosing 2003-03-19 15:15:40 Re: request for sql3 compliance for the update command
Previous Message Bruce Momjian 2003-03-19 14:36:50 Re: request for sql3 compliance for the update command