create trigger table1_bt
before delete
on table1
for each row
  my_name varchar2(30) := 'TABLE1_BT';
  call_stack VARCHAR2(2000);
begin

  -- this looks to see if there is a second occurrence of this trigger
  --  in the call stack. If it is, the round trip is occurring and you should
  --  abort. Assumes that your TRIGGER names aren't similar enough that
  --  an INSTR test would be positive for both TRIGGER names. For example,
  --  the following 2 names are too similar: TABLE_BT and TABLE_BT2, while
  --  these would be ok: TABLE_BT and TABLE2_BT. Using a stack would 
  --  get you around this potential mistake, but, this stack already exists for
  --  you to search through.

  if instr(dbms_utility.format_call_stack, my_name, 1, 2) > 0 then
    return;
  end if;

  delete 
  from table2
  where some_field = :OLD.some_field;


  
end table1_bt;