From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
---|---|
To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | "Hiroshi Saito" <z-saito(at)guitar(dot)ocn(dot)ne(dot)jp>, <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: "AS" by the syntax of table reference.(8.4 proposal) |
Date: | 2008-02-09 11:13:09 |
Message-ID: | 87hcgil6wq.fsf@oxford.xeocode.com |
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Lists: | pgsql-hackers |
"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
>> But yeah, c_expr isn't enough. We really need {a,b}_expr sans postfix
>> expressions.
>
> How's that going to help? As long as postfix operators exist at all,
>
> SELECT a + b, ...
>
> is going to be ambiguous, and no amount of grammar magic changes that.
> We could force the parser into using one interpretation or the other,
> but it would still be wrong for some folks.
Sure, just like a + + b is ambiguous. We define an arbitrary choice and tell
people to put parentheses if they want the other. It's not too hard to write
SELECT (a +) b, ...
if you want an alias. Besides, nobody uses postfix expressions anyways. It
would be a pain if it worked the other way and you had to write (a + b) all
the time.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Get trained by Bruce Momjian - ask me about EnterpriseDB's PostgreSQL training!
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