Обсуждение: Re: [HACKERS] Table aliases in delete statements?

>Bruce Momjian <pgman@candle.pha.pa.us>

>
>> emkxp01=> delete from deltest s1 where s1.respdate not in ( select 
>> min(s2.respdate) from deltest s2 where s1.sessionid = s2.sessionid);
>> ERROR:  parser: parse error at or near "s1"
>> emkxp01=> 
>
>Don't use s1.  Just refer to native deltest in the subquery.  That
>should reference the outer table.

That doesn't seem to work as 3 rows are deleted and not just the
two duplicates.

emkxp01=> delete from deltest where respdate not in ( select min(s2.respdate) 
from deltest s2 where sessionid = s2.sessionid);
DELETE 3
emkxp01=> select * from deltest;sessionid |           respdate           
-----------+------------------------------        1 | Tue 07 Dec 22:32:01 1999 GMT
(1 row)

emkxp01=> 

Keith.

> >Don't use s1.  Just refer to native deltest in the subquery.  That
> >should reference the outer table.
> 
> That doesn't seem to work as 3 rows are deleted and not just the
> two duplicates.
> 
> emkxp01=> delete from deltest where respdate not in ( select min(s2.respdate) 
> from deltest s2 where sessionid = s2.sessionid);
> DELETE 3
> emkxp01=> select * from deltest;
>  sessionid |           respdate           
> -----------+------------------------------
>          1 | Tue 07 Dec 22:32:01 1999 GMT
> (1 row)

No.  Use:

emkxp01=> delete from deltest where respdate not in ( select min(s2.respdate) 
from deltest s2 where deltest.sessionid = s2.sessionid);                     ^^^^^^^

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