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

["Gau, Hans-Jürgen" <Hans-Juergen(dot)Gau(at)LGN(dot)Niedersachsen(dot)de>]

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 
		WHERE t3.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(at)free(dot)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 t1
 SET 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 t1
 SET 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) IS NOT
NULL;

A PostgreSQL-compliant version could also be:
UPDATE table1 t1
 SET id = t3.id
 FROM table2 t2, table3 t3
 WHERE 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 t1
 SET id = t3.id
 FROM table2 t2
  INNER JOIN
   (SELECT t.id, t.field FROM table3 t WHERE t.id IS NOT NULL) t3
  ON t3.field = t2.field
  WHERE t2.id = t1.id AND t3.id <> t1.id;

Hoping a satisfying solution is up.

--
nha / Lyon / France.