| From: | Richard Huxton <dev(at)archonet(dot)com> |
|---|---|
| To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Cc: | David Salisbury <salisbury(at)globe(dot)gov>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: default value returned from sql stmt |
| Date: | 2012-03-30 08:22:09 |
| Message-ID: | 4F756D31.2050009@archonet.com |
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| Lists: | pgsql-general |
On 30/03/12 08:46, Pavel Stehule wrote:
> 2012/3/30 Richard Huxton<dev(at)archonet(dot)com>:
>> On 29/03/12 23:28, Pavel Stehule wrote:
>>>
>>> select anum from t1 where anum = 4
>>> union all select 100 limit 1;
>>
>>
>> I'm not sure the ordering here is guaranteed by the standard though, is it?
>> You could end up with the 4 being discarded.
>
> A order is random for only "UNION", "UNION ALL" should to respect
> order. But I didn't check it in standard.
Let's put it this way - a quick bit of googling can't find anything that
says the order *is* guaranteed, and (almost?) no other operations do so
by default.
--
Richard Huxton
Archonet Ltd
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