From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Do FROM items of different schemas conflict? |
Date: | 2002-03-08 22:27:39 |
Message-ID: | 200203082227.g28MRdI28853@candle.pha.pa.us |
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Lists: | pgsql-hackers |
Tom Lane wrote:
> Okay folks, time to put on your language-lawyer hats ...
>
> I have been trying to puzzle out the SQL rules concerning whether two
> FROM items conflict in the presence of schemas. It is entirely clear
> that one is not allowed to write
>
> SELECT * FROM tab1, tab1;
>
> since this introduces two FROM items of the same name in the same scope.
> One *can* write
>
> SELECT * FROM tab1, tab1 AS x;
>
> since the alias x effectively becomes the name of the second FROM item.
> But what about
>
> SELECT * FROM schema1.tab1, schema2.tab1;
From my simplistic understanding, I would say if we allowed this, we
would have to require the schema designtation be on every reference to
tab1 in the query. Is that something we can do?
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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