WG: WG: sql-porting-problem oracle to postgresql with UPDAT E/IS NOT NULL

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От Gau, Hans-Jürgen
Тема WG: WG: sql-porting-problem oracle to postgresql with UPDAT E/IS NOT NULL
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Msg-id 670F563845D6B34189933C9C7322B4872C0A07@LV-MX-00002-V02.LV.ads.niedersachsen.de
обсуждение исходный текст
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it runs without alias t1. before fieldname id after SET, so:

UPDATE table1 t1     SET id =         (SELECT t3.id FROM table2 t2,table3 t3, table1 t1     WHERE t3.field = t2.field
         AND t2.id = t1.id         AND t1.id <> t3.id) WHERE     (SELECT t3.id FROM table2 t2,table3 t3, table1 t1
WHEREt3.field = t2.field         AND t2.id = t1.id         AND t1.id <> t3.id) IS NOT NULL; 

Of course, simply...

Thanks for the help!


-----Ursprüngliche Nachricht-----
Von: nha [mailto:lyondif02@free.fr]
Gesendet: Mittwoch, 29. Juli 2009 13:04
An: Gau, Hans-Jürgen
Cc: PgSQL-sql
Betreff: Re: WG: [SQL] sql-porting-problem oracle to postgresql with
UPDATE/IS NOT NULL

Hello again,

Le 29/07/09 12:21, nha a écrit :
> Hello,
>
> Le 29/07/09 11:48, Gau, Hans-Jürgen a écrit :
>> Sorry, it's a lapse by copying and simplification the original version.
that
>> is correct:
>>
>> UPDATE table1 t1
>>     SET (t1.id) =
>>         (SELECT t3.id FROM table2 t2,table3 t3, table1 t1
>>         WHERE t3.field = t2.field
>>             AND t2.id = t1.id
>>             AND t1.id <> t3.id)
>>     WHERE
>>         (SELECT t3.id FROM table2 t2,table3 t3, table1 t1
>>         WHERE t3.field = t2.field
>>             AND t2.id = t1.id
>>             AND t1.id <> t3.id) IS NOT NULL;
>> [...]
>> the solution brought by Daryl Richter has no effect.
>
> There is one mistake [...]

To be concrete, a valid version would be:
UPDATE table1 t1SET id = (something)WHERE (anotherthing);

> Except this point, the query is valid although I am not sure the result
> is always what you may expect [...]

To "join" table1 column (assumed: id) to the subquery (sub-select here)
expression, table1 recall is not relevant in the subquery. Moreover an
alias "t1" is already defined to table1 (at the beginning of the statement).

A more suitable version would be:
UPDATE table1 t1SET id = (SELECT t3.id FROM table2 t2, table3 t3 WHERE t3.field = t2.field AND t2.id = t1.id AND t1.id
<>t3.id)WHERE (SELECT t3.id FROM table2 t2, table3 t3 WHERE t3.field = t2.field AND t2.id = t1.id AND t1.id <> t3.id)
ISNOT 
NULL;

A PostgreSQL-compliant version could also be:
UPDATE table1 t1SET id = t3.idFROM table2 t2, table3 t3WHERE t3.field = t2.field AND t2.id = t1.id AND t1.id <> t3.id
AND
t3.id IS NOT NULL;

A PostgreSQL-compliant and faster version may be:
UPDATE table1 t1SET id = t3.idFROM table2 t2 INNER JOIN  (SELECT t.id, t.field FROM table3 t WHERE t.id IS NOT NULL) t3
ONt3.field = t2.field WHERE t2.id = t1.id AND t3.id <> t1.id; 

Hoping a satisfying solution is up.

--
nha / Lyon / France.



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