CREATE OR REPLACE FUNCTION myrecordset
(in cnt integer,out id integer, out name text,out b bit)
RETURNS SETOF record LANGUAGE 'plpgsql'  AS
$body$
declare    x integer= 0 ;
begin
 while x<cnt loop
   id=x;    name='x^2='||x*x;    b= 1 ;
   x=x+ 1 ;return next;
 end loop;
end $body$;

select * from myrecordset( 100 ) where id> 80 ;

CREATE OR REPLACE FUNCTION myrecordset
(in cnt integer, out id integer, out name text, out b bit)
RETURNS SETOF record LANGUAGE 'plpgsql'  AS $body$
declare    x integer= 0 ;
              r record;
begin
for r in select oid,pg_class.relname, 1  as ff from pg_class loop
 id=r.oid;
 name=r.relname;
 b=r.ff;
 return next;
end loop;

while x<cnt loop
   id=x;    name='x^2='||x*x;  b= 1 ;
   x=x+ 1 ;return next;
 end loop;
end $body$;
select * from myrecordset( 100 );

EXECUTE 'UPDATE tbl SET '
        || quote_ident(colname)
        || ' = '
        || newvalue
        || ' WHERE key = '
        || quote_literal(keyvalue);

create or replace function MayRecords ( in sql text)
RETURNS SETOF record AS
$body$
declare rr record;
begin
FOR rr in execute (sql) LOOP

           return next rr ;
END LOOP;
end
$body$
LANGUAGE 'plpgsql';

select  * from  MyRecords('select oid::integer,relname::text from pg_class') as (id integer,name text)