Re: plpgsql returning array

[Jean-Christophe Roux <jcxxr@xxxxxxxxx>]

Marc,

Thanks for the tip. It does the job! This "return setof/next" is quite new to me; I am going to spend some time to understand it and see how it can improve codes.

----- Original Message ----
From: Marc McIntyre <mmcintyre@xxxxxxxxx>
To: Jean-Christophe Roux <jcxxr@xxxxxxxxx>
Cc: pgsql-php@xxxxxxxxxxxxxx
Sent: Sunday, October 15, 2006 2:11:30 AM
Subject: Re: [PHP] plpgsql returning array

You should use a set returning function. Your function can be rewritten
as a set returning function like so:

CREATE OR REPLACE FUNCTION foo()
  RETURNS SETOF text AS
$BODY$
declare
    a text;
    b text;
    arr text[];
    i INTEGER := 0;
begin
    a = 'a';
    b = 'b';
    arr[0] = a;
    arr[1] = b;
  
    FOR i IN 0..array_upper(arr, 1) LOOP
        RETURN NEXT arr[i];
    END LOOP;

end;
$BODY$
  LANGUAGE 'plpgsql' VOLATILE;


And to call the function:

marc=# select * from foo();
foo
-----
a
b
(2 rows)

Notice that to return a value within the set you use the construct
"RETURN NEXT". Set returning functions are generally faster than array
returning functions, and are also more useful. For instance you can use
set returning functions in sub selects like so:

Select * from table where col in (select * from foo())

You can also use a where clause within the select statement ie.

marc=# select * from foo() as x where x = 'a';
x
---
a
(1 row)

So a set returning function is like a derived table.

In php, the result from a set returning function would be the same as
querying a table.

Jean-Christophe Roux wrote:
> Hello,
> in Postgresql, I have a function like this
>
> CREATE OR REPLACE FUNCTION foo()
>   RETURNS text[] AS
> $BODY$
> declare
>     a text;
>     b text;
>     arr text[];
> begin
>     a = 'a';
>     b = 'b';
>     arr[0] = a;
>     arr[1] = b;
>     return arr;
> end;
> $BODY$
>   LANGUAGE 'plpgsql' VOLATILE;
>
> In PHP I would like to read my returned arr.
> <?php
>             $message = pg_fetch_result(pg_query("select foo()"),0,0);
>             print_r($message);
> ?>
> prints something like:
> [0:1]={a,b}
>
>
> I could parse that results, as a string but I'd rather have a nice
> array. Any idea how I should change the function and/or the php codes?
> Thanks in advance
> Jean
>