Re: Consecutive operators not recognized without whitespace

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Chris Angelico <rosuav(at)gmail(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Consecutive operators not recognized without whitespace
Date: 2011-12-13 00:01:18
Message-ID: 14445.1323734478@sss.pgh.pa.us
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Chris Angelico <rosuav(at)gmail(dot)com> writes:
> 1) Set a bit:
> UPDATE tablename SET flags=flags|8 WHERE id=1234

> 2) Clear a bit:
> UPDATE tablename SET flags=flags&~8 WHERE id=1234

> However, the second statement fails; the Postgres parser tries to find
> a single "&~" operator, instead of using the unary ~ and then the
> binary &. Putting a space between the two symbols makes it work fine,
> but I was wondering: Is this intentional behavior?

Yes. Postgres allows multi-character operator names, so you need a
space in general. There are exceptions for certain single-character
operator names that are defined in the SQL spec (eg, a+-b is required
by spec to parse as two operators), but & and ~ are not in that list.
You can find the details in the fine manual, probably somewhere in
the "Syntax" chapter.

regards, tom lane

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