Re: MERGE ... RETURNING

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От Vik Fearing
Тема Re: MERGE ... RETURNING
Дата
Msg-id c56939d9-9bba-3db1-16c9-d99dec3f0f04@postgresfriends.org
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Ответ на Re: MERGE ... RETURNING  (Jeff Davis <pgsql@j-davis.com>)
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On 7/13/23 01:48, Jeff Davis wrote:
> On Wed, 2023-07-12 at 03:47 +0200, Vik Fearing wrote:
> 
>> There is no RETURNING clause in Standard SQL, and the way they would
>> do
>> this is:
>>
>>       SELECT ...
>>       FROM OLD TABLE (
>>           MERGE ...
>>       ) AS m
>>
>> The rules for that for MERGE are well defined.
> 
> I only see OLD TABLE referenced as part of a trigger definition. Where
> is it defined for MERGE?

Look up <data change delta table> for that syntax.  For how MERGE 
generates those, see 9075-2:2023 Section 14.12 <merge statement> General 
Rules 6.b and 6.c.

> In any case, as long as the SQL standard doesn't conflict, then we're
> fine. And it looks unlikely to cause a conflict right now that wouldn't
> also be a conflict with our existing RETURNING clause elsewhere, so I'm
> not seeing a problem here.

I do not see a problem either, which was what I was trying to express 
(perhaps poorly).  At least not with the syntax.  I have not yet tested 
that the returned rows match the standard.
-- 
Vik Fearing




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