declare

  v_clnt number := 1;
  v_subs number := 1;
  Result number;
  tbl_name varchar2(2000) := 't';
  
  l_stmnt varchar2(32767) := 
           'with t(in_balance_$, main_clnt_id, subs_subs_id, rsta_rsta_id) as (select 1000, 1, 1, null from dual connect by level <=5)'||
                'select sum(in_balance_$) from ' || tbl_name 
             || ' where main_clnt_id = :main_clnt_id '
             || ' and subs_subs_id = :subs_subs_id'
             || ' and rsta_rsta_id is null' 
          ;  
  type t_cur is ref cursor;
  c_cur t_cur;
  ------------------------------------------------------------
  cursor c (v_period date, v_clnt number, v_subs number) is 
  with t1 (period, in_balance_$, main_clnt_id, subs_subs_id, rsta_rsta_id) as (
          select date'2018-01-01', 1000, 1, 1, null from dual connect by level <=5
       )
     , t2 (period, in_balance_$, main_clnt_id, subs_subs_id, rsta_rsta_id) as (
          select date'2018-02-01', 1000, 1, 1, null from dual connect by level <=8
       )
  select sum(in_balance_$) s from t1 
   where period = v_period -- for partition pruning (even on standard edition)
     and main_clnt_id = v_clnt and subs_subs_id = v_subs and rsta_rsta_id is null
  UNION ALL
  select sum(in_balance_$) from t2 
   where period = v_period -- for partition pruning
     and main_clnt_id = v_clnt and subs_subs_id = v_subs and rsta_rsta_id is null
  ;
              
begin
------------------------------  
 execute immediate l_stmnt
  into Result
  using in v_clnt, in v_subs; 
 dbms_output.put_line(Result);
------------------------------ 
 open c_cur for l_stmnt using in v_clnt, in v_subs;
 loop
   fetch c_cur into Result;
   exit when c_cur%notfound;
 end loop;
 close c_cur;
 dbms_output.put_line(Result);
------------------------------ 
 for i in c (date'2018-01-01', v_clnt, v_subs) loop
   dbms_output.put_line(i.s);
 end loop;
end;