sql>create table A
  2  (
  3  A_ID NUMBER(9) PRIMARY KEY
  4  );
 
Table created.
 
sql>create table B
  2  (
  3  B_ID NUMBER(9) PRIMARY KEY
  4  );
 
Table created.
 
sql>alter table B
  2  add constraint FK_B_A foreign key (B_ID)
  3  references A (A_ID) on delete cascade;
 
Table altered.
 
sql>create or replace trigger AFTER_A AFTER DELETE ON A
  2  BEGIN
  3  dbms_output.put_line('AFTER A');
  4  END;
  5  /
 
Trigger created.
 
sql>create or replace trigger AFTER_B AFTER DELETE ON B
  2  BEGIN
  3  dbms_output.put_line('AFTER B');
  4  END;
  5  /
 
Trigger created.
 
sql>insert into a values (1);
 
1 row created.
 
sql>insert into b values (1);
 
1 row created.
 
sql>commit;
 
Commit complete.
 
sql>set serveroutput on
 
sql>delete from a where a_id = 1;
<b>AFTER B
AFTER A</b>
 
1 row deleted.