The following bug has been logged online:

Bug reference: 1677
Logged by: Julien Vallet
Email address: julien.vallet (AT) density-tech (DOT) com
PostgreSQL version: 8.0 & 8.0.3
Operating system: Windows XP
Description: Bug in select with Union
Details:

I think there is a problem with the select statement with Union.

Firstable, I create 3 tables (tuserprofileopp, tprofileopp and
tgroupprofileopp).

CREATE TABLE tuserprofileopp
(
internalkey int8 NOT NULL,
CONSTRAINT tuserprofileopp_pkey PRIMARY KEY (internalkey)
);

CREATE TABLE tprofileopp
(
internalkey int8 NOT NULL,
CONSTRAINT tprofileopp_pkey PRIMARY KEY (internalkey)
);

CREATE TABLE tgroupprofileopp
(
internalkey int8 NOT NULL,
manager_id int8,
CONSTRAINT tgroupprofileopp_pkey PRIMARY KEY (internalkey)
);

Then, I write this request:
select *
from
(
select
internalKey, null as manager_id, 0 as clazz_
from TProfileOPP
union select
internalKey, null as manager_id, 1 as clazz_
from TUserProfileOPP
union select
internalKey, manager_id, 2 as clazz_
from TGroupProfileOPP
)
this_;

The result is "ERROR: UNION types text and bigint cannot be matched"

If I do
"select *
from
(
select
internalKey, null as manager_id, 0 as clazz_
from TProfileOPP
union select
internalKey, manager_id, 2 as clazz_
from TGroupProfileOPP
)
this_;", It works.

Thank you.

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"Julien Vallet" <julien.vallet (AT) density-tech (DOT) com> writes:
This is the identical issue reported here:
http://archives.postgresql.org/pgsql...2/msg00008.php
See also this thread:
http://archives.postgresql.org/pgsql...2/msg00693.php

The short answer is that what you wrote is illegal per the SQL spec
(which doesn't allow NULL to be used in ways where a type can't be
ascribed immediately). While we'd like to accept it, we have
not figured out a rule that doesn't break the spec in other ways.
For now I'd recommend casting the NULLs explicitly.

regards, tom lane

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On Mon, 23 May 2005 11:54 pm, Tom Lane wrote:
Can we spit out an error that is slightly more relevant? Maybe print
a warning/error that NULL was used without a type?

Regards

Russell Smith
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