From: Dimitri Fontaine <dfontaine@hi-media.com>
To: Julius Tuskenis <julius@nsoft.lt>
Cc: pgsql-admin@postgresql.org
Subject: Re: operator does not exist
Organization: Hi-Media
References: <4BA32695.1090402@nsoft.lt>
User-Mail-Address: dfontaine@hi-media.com
Date: Fri, 19 Mar 2010 10:16:01 +0100
In-Reply-To: <4BA32695.1090402@nsoft.lt> (Julius Tuskenis's message of "Fri,
	19 Mar 2010 09:24:05 +0200")
Message-ID: <87d3z0wu26.fsf@hi-media-techno.com>
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Julius Tuskenis <julius@nsoft.lt> writes:

> select '1' = 1 results in true

This is a undecorated literal, which PostgreSQL will cast as integer
when it discovers that's what makes sense.

> while select sum(msg_price) from messages where msg_itemid = 0 results in
> error:
> ERROR:  operator does not exist: character varying = integer
> LINE 1: select sum(msg_price) from messages where msg_itemid = 0

Here, msg_itemid is known to be a varchar, and 0 is a numeric literal,
which is in the range of an integer, so the type is resolved as an
integer. Now the = operator does not exist for varchar, integer.

> I will add the operator ant then we'll fix the queries, but is the first
> example ok? Should it not raise error ?

Not as written. Try to decorate the literal to force PostgreSQL into
considering it of the type you have in mind:

  SELECT text '1' = 1;

Or even do a cast, this way:

  SELECT '1'::text = 1;

Regards,
-- 
dim