Re: most idiomatic way to iterate over an associative array?

On May 7, 4:37 pm, "stephen O'D" <stephen.odonn..._at_gmail.com> wrote:
> On May 7, 5:28 pm, Mark D Powell <Mark.Pow..._at_eds.com> wrote:
>
>
>
>
>
> > On May 7, 4:07 am, Robert Klemme <shortcut..._at_googlemail.com> wrote:
>
> > > On May 7, 6:51 am, m..._at_pixar.com wrote:
>
> > > > This is what I'm doing now... is there a better way?
> > > > It would be great if there were some construct such
> > > > as 'for i in x begin ... end;'
>
> > > >     i := x.first;
> > > >     loop
> > > >         dbms_output.put_line(i);
> > > >         exit when i = x.last;
> > > >         i := x.next(i);
> > > >     end loop;
>
> > > > Many TIA!
> > > > Mark
>
> > > This will break for empty collections.  You can do
>
> > > SQL> set serverout on
> > > SQL> DECLARE  TYPE population_type IS TABLE OF NUMBER INDEX BY
> > > VARCHAR2(64);
> > >   2    continent_population population_type;
> > >   3    which VARCHAR2(64);
> > >   4  BEGIN
> > >   5    dbms_output.put_line('-----------');
> > >   6
> > >   7    which := continent_population.FIRST;
> > >   8    while which is not null loop
> > >   9      dbms_output.put_line(which || ' -> ' ||
> > > continent_population(which));
> > >  10      which := continent_population.NEXT(which);
> > >  11    end loop;
> > >  12
> > >  13    dbms_output.put_line('-----------');
> > >  14
> > >  15    continent_population('Australia') := 30000000;
> > >  16    continent_population('Antarctica') := 1000; -- Creates new
> > > entry
> > >  17    continent_population('Antarctica') := 1001; -- Replaces
> > > previous value
> > >  18
> > >  19    which := continent_population.FIRST;
> > >  20    while which is not null loop
> > >  21      dbms_output.put_line(which || ' -> ' ||
> > > continent_population(which));
> > >  22      which := continent_population.NEXT(which);
> > >  23    end loop;
> > >  24
> > >  25    dbms_output.put_line('-----------');
> > >  26  END;
> > >  27  /
> > > -----------
> > > -----------
> > > Antarctica -> 1001
> > > Australia -> 30000000
> > > -----------
>
> > > PL/SQL procedure successfully completed.
>
> > > SQL>
>
> > > Cheers
>
> > > robert
>
> > > seehttp://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/collec......
>
> > I think I would consider the For I in 1..n construct
>
> > UT1 > l
> >   1  declare
> >   2  type t_array is table of varchar2(10) index by binary_integer;
> >   3  t_list   t_array;
> >   4  begin
> >   5  t_list(1) := 'one';
> >   6  t_list(2) := 'two';
> >   7  t_list(3) := 'three';
> >   8  t_list(4) := 'four';
> >   9  t_list(5) := 'five';
> >  10  for I in 1..t_list.last loop
> >  11    dbms_output.put_line(t_list(I));
> >  12  end loop;
> >  13* end;
> > UT1 > /
> > one
> > two
> > three
> > four
> > five
>
> > PL/SQL procedure successfully completed.
>
> > Again as Robert warned in his solution the array should not be empty.
>
> > HTH -- Mark D Powell --
>
> I am fairly sure if you do
>
> for i in 1 .. v_array.count loop
>   null;
> end loop;
>
> It will happily handle an empty array (don't have access to Oracle
> right now to check).- Hide quoted text -
>
> - Show quoted text -

Your are probably correct. My quick test failed however using table.count instead of table.last like I did would probably be a better idea and would be worth testing. It has been over 3 years since I wrote any PL/SQL code worth mentioning. After posting I though I should have tested table.first .. table.last also. Maybe tomorrow I will find some spare time.

• Mark D Powell --