for select t1.grp
        from table1 t1
          join table2 t2 using(id)
        group by t1.grp
  as cursor c
  do begin

    select count(*)
      from table1 t1
        join table2 t2 using(id)
        join table3 t3 using(id1)
      where t1.grp=:с.grp
    into :tmp;

  end

  for select t1.grp
        from table1 t1
          join table2 t2 using(id)
        group by t1.grp
  as cursor c
  do begin
  end 

  select count(*)
    from table1 t1
      join table2 t2 using(id)
      join table3 t3 using(id1)
    where t1.grp=1

  for select t1.grp
        from table1 t1
          join table2 t2 using(id)
        group by t1.grp
  as cursor c
  do begin

    tmp_grp = c.grp;

    select count(*)
      from table1 t1
        join table2 t2 using(id)
        join table3 t3 using(id1)
      where t1.grp=:tmp_grp
    into :tmp;

  end