1) Create new database called dbtest
2) Run this script:

BEGIN

  declare  i integer;
  DECLARE   my_crs        CURSOR FOR my_stmt;
  DECLARE   my_crs2       CURSOR FOR my_stmt2;

  execute immediate 'CREATE TABLE "t1" (f1 integer, f2 integer)';
  execute immediate 'CREATE TABLE "t2" (f1 integer, f2 integer)';

  execute immediate '
CREATE TABLE "t_future_groups" ("f_group_number" integer ,"f_item_number" integer,
      CONSTRAINT "ix_mainkey" PRIMARY KEY ("f_group_number", "f_item_number")
) ';

  execute immediate '
     insert into dbtest.t_future_groups (f_group_number,f_item_number) values (1,5),(1,10)  
,(1,15),(1,20),(1,25),(1,30),(1,35),(1,40),(1,45),(1,50),(1,55),(1,60),(1,65),(1,70),(1,75),(1,80)
,(1,85),(1,90),(1,95),(1,100)     ';


   PREPARE my_stmt FROM  'insert into dbtest.t1 (f1,f2) values (?,?) ';
   PREPARE my_stmt2 FROM  'insert into dbtest.t2 (f1,f2) values (?,?) ';
   set i=1;
   repeat      
      EXECUTE my_stmt USING i,i;
      if i mod 50 <>0 then 
         EXECUTE my_stmt2 USING i,i;
      end if;
      set i=i+1;
   until i=501 end repeat;

END

3) Run this SQL statement:

select * from dbtest.t1 t1

INNER JOIN dbtest.t2 t2 ON  (t1.f1 = t2.f1)
  
inner JOIN dbtest.t_future_groups tfg ON
    ((tfg.f_group_number, tfg.f_item_number) = (1,t2.f1))

order by f1