Обсуждение: returning setof in plpgsql

I have a function that I want to return setof a table in plpgsql.

Here is what I have:

CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
DECLARE aname ALIAS FOR $1; rec RECORD;
BEGIN select into rec * from accounts where accountname = aname; return rec;
END;'
LANGUAGE 'plpgsql';

This seems to hang when I attempt to select it using:

select accountid(
lookup_account('some account')),
accountname(lookup_account('some account')),
type(lookup_account('some account')),
balance(lookup_account('some account'));

Does anyone see a problem w/ my approach??

On Tuesday 21 Jan 2003 10:40 am, David Durst wrote:
> I have a function that I want to return setof a table in plpgsql.
>
> Here is what I have:
>
> CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
> DECLARE
>   aname ALIAS FOR $1;
>   rec RECORD;
> BEGIN
>   select into rec * from accounts where accountname = aname;
>   return rec;
> END;'
> LANGUAGE 'plpgsql';
>
> This seems to hang when I attempt to select it using:
>
> select accountid(
> lookup_account('some account')),
> accountname(lookup_account('some account')),
> type(lookup_account('some account')),
> balance(lookup_account('some account'));
>
> Does anyone see a problem w/ my approach??

Hi David,

I've never done this but I seem to remember seeing something about this 
recently. 

Firstly, I think you need 7.3.1 to do this.

You then have to create a 'type' as being a set of your table.  You then 
define the function as returning that type.

Sorry I can't be more specific, but as I said, I've never done it.

Gary

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"David Durst" <ddurst@larubber.com> writes:
> CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
> DECLARE
>   aname ALIAS FOR $1;
>   rec RECORD;
> BEGIN
>   select into rec * from accounts where accountname = aname;
>   return rec;
> END;'
> LANGUAGE 'plpgsql';

As written, this function can only return a single row (so you hardly
need SETOF).  If you intend that it be able to return multiple rows
when accountname is not unique, then you'll need a loop and RETURN NEXT
commands.  It'd probably be less tedious to use a SQL-language function:

CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
select * from accounts where accountname = $1'
language sql;

> This seems to hang when I attempt to select it using:

> select accountid(
> lookup_account('some account')),
> accountname(lookup_account('some account')),
> type(lookup_account('some account')),
> balance(lookup_account('some account'));

It works for me (in 7.3), but in any case that's a bad approach: you're
invoking the function four times, independently.  Better is

select accountid,accountname,type,balance
from lookup_account('some account');

(again, this syntax requires 7.3)
        regards, tom lane

I thought we had an example of this type of function in the docs, but we
don't.  Here is one:
http://www.brasileiro.net:8080/postgres/cookbook/view-recipes.adp?section_id=535&format=long

---------------------------------------------------------------------------

Tom Lane wrote:
> "David Durst" <ddurst@larubber.com> writes:
> > CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
> > DECLARE
> >   aname ALIAS FOR $1;
> >   rec RECORD;
> > BEGIN
> >   select into rec * from accounts where accountname = aname;
> >   return rec;
> > END;'
> > LANGUAGE 'plpgsql';
> 
> As written, this function can only return a single row (so you hardly
> need SETOF).  If you intend that it be able to return multiple rows
> when accountname is not unique, then you'll need a loop and RETURN NEXT
> commands.  It'd probably be less tedious to use a SQL-language function:
> 
> CREATE FUNCTION lookup_account(varchar(32)) RETURNS SETOF accounts AS '
> select * from accounts where accountname = $1'
> language sql;
> 
> > This seems to hang when I attempt to select it using:
> 
> > select accountid(
> > lookup_account('some account')),
> > accountname(lookup_account('some account')),
> > type(lookup_account('some account')),
> > balance(lookup_account('some account'));
> 
> It works for me (in 7.3), but in any case that's a bad approach: you're
> invoking the function four times, independently.  Better is
> 
> select accountid,accountname,type,balance
> from lookup_account('some account');
> 
> (again, this syntax requires 7.3)
> 
>             regards, tom lane
> 
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