create table table1 (f1 integer, f2 integer, f3 integer);
CREATE PROCEDURE a1
RETURNS (
    F1 VARCHAR( 50 ),
    F2 VARCHAR( 50 ),
    F3 VARCHAR( 50 ))
AS
begin
  delete from table1;
  insert into table1 values ( 1 , 2 , 3 );
  insert into table1 values ( 4 , 5 ,null);
  insert into table1 values ( 7 , 8 , 9 );
  for select 'Сумма1= ' || cast(sum(f1) as varchar( 5 )),
             'Сумма2 = ' || cast(sum(f2) as varchar( 7 )),
             'Сумма3 = ' || cast(sum(f3) as varchar( 10 ))
      from table1
      into :F1, :F2, :F3
  do
  suspend;
end;

select 'Сумма1= ' || cast(sum(f1) as varchar( 5 )),
             'Сумма2 = ' || cast(sum(f2) as varchar( 7 )),
             'Сумма3 = ' || cast(sum(f3) as varchar( 10 ))
      from table1