Re: [HACKERS] Re: PL/PGSQL function with parameters

Tom Lane wrote:
> Michael Ansley <Michael.Ansley@intec-telecom-systems.com> writes:
> > CREATE FUNCTION table_count(varchar) RETURNS integer AS '
> > DECLARE
> >  SQL varchar;
> >  RES integer;
> > BEGIN
> >  SQL = ''SELECT * INTO temp1 FROM '' || $1;
> >  EXECUTE SQL;
> >  SELECT count(*) INTO RES FROM temp1;
> >  RETURN(RES)
> > END;
> > '
> > LANGUAGE 'plpgsql';
>
> > What I couldn't get it to do was to select directly into the variable RES.
>
> I tried this, and it seems that "SELECT ... INTO foo" is not executed
> correctly by EXECUTE --- the INTO is handled as an ordinary select-into-
> table construct rather than plpgsql's select-into-variable.
>
> While I have not looked closely, I seem to recall that plpgsql handles
> INTO by stripping that clause out of the statement before it's passed to
> the SQL engine.  Evidently that's not happening in the EXECUTE case.
>
> Jan, do you agree this is a bug?  Is it reasonable to try to repair it
> for 7.1?  If we do not change the behavior of EXECUTE now, I fear it
> will be too late --- some people will come to depend on the existing
> behavior.
   EXECUTE simply takes the string expression and throws it into   SPI_exec() without parsing. Changing that for  7.1
is *not*   possible.
 
   The above can be accomplished by
       DECLARE         ROW record;         RES integer;       BEGIN         FOR ROW IN EXECUTE             ''SELECT
count(*)AS N FROM '' || $1         LOOP           RES := N;         END LOOP;         RETURN RES;       END;
 
   Not  as  elegant  as  it  should  be,  but at least possible.   There's much to be done for a future version of
PL/pgSQL,but   better  support  for  dynamic SQL needs alot of functionality   added to the main parser and the SPI
manager in  the  first   place.
 


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
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