Re: BUG #1540: Enhancement request: 'ambiguous' column reference

From: Neil Conway <neilc(at)samurai(dot)com>
To: Richard Neill <postgresql(at)richardneill(dot)org>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #1540: Enhancement request: 'ambiguous' column reference
Date: 2005-03-14 03:00:41
Message-ID: 4234FE59.4090908@samurai.com
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Richard Neill wrote:
> I think that the first query ought to succeed, since although priceband is
> ambiguous (it could mean either tbl_prices.priceband or
> tbl_instruments.priceband), the information in the WHERE clause means that
> they are explicitly equal, and so it doesn't matter which one we use.

Well, it just means the type's equality operator returns true for these
two values -- I'm not sure it is wise to assume they are completely
interchangeable.

More generally, it makes sense to me that resolution of column
references is a property of the syntax of a statement, not something
derived from its semantics (e.g. the fact that we can infer for some
particular statement that two columns are equal).

-Neil

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