create procedure A(in pStart date, in pEnd date)
begin
  create table #rep_a(ClientId char( 10 ), Amount money);
  insert into #rep_a select ClientId, sum(Amount) from payments where payment_date between pStart and pEnd;
  select * from #rep_a;
end;

create procedure B(in pStart date, pEnd date, pClientId char( 10 ))
begin
  declare pS date; declare pE date;
  declare crsrA no scroll cursor for call A(pS, pE)
  create table #rep_b(Amount money);

  set pS = pStart; set pE=pEnd;
  open crsrA;
   loop
    fetch crsrA into mClientId, mAmount;
    insert into #rep_b values(mClientId, mAmount);
   end loop;
  close crsrA;
  // ну или можно напрямую обращатся к временным таблицам
  open crsrA;
  insert into #rep_b from #rep_a where #rep_a.ClientId=pClientId;
  close crsrA;
end;