From: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: NULL value in subselect in UNION causes error |
Date: | 2007-01-26 20:46:50 |
Message-ID: | 45BA68BA.2080204@Yahoo.com |
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Lists: | pgsql-hackers |
On 1/26/2007 3:41 PM, Tom Lane wrote:
> Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
>> Checked it against HEAD and 8.2:
>> postgres=# select 1, 1, 1 union select * from (select 2, null, 2) two;
>> ERROR: failed to find conversion function from "unknown" to integer
>
> It's always done that. The SQL spec would tell you that you have to
> cast the null to some specific type. We allow untyped nulls in contexts
> where we can derive a type from reasonably nearby context, but an
> integer two levels up and over in another union arm isn't very nearby
> IMHO. So I'm not particularly concerned about making this work ...
That explains. Thanks.
Jan
--
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