How to alter the constraint for on delete cascade

Question

Hi Guys,
I have a table which has 5 level of child tables .But all the child tables have the foreign keys without on delete cascade.But I have to delete a data in the parent table .One method I thought to change the child table constraints to ON DELETE CASCADE then delete the record and after that again to change the constraints with out the ON DELETE CASCADE.Please let me know wheather these is possible or not .If not is there any other alternatives to achive this.
Any suggestions would be highly appreciated.
Thanks in advance
Prafulla

Answer 1

I think you need to drop and recreate your FKs.
See my example here.
create table TEST1
  id       NUMBER(12) not null,
  anything VARCHAR2(20)
alter table TEST1
  add constraint PK_TEST1 primary key (ID);
create table TEST2
  id2  NUMBER(12) not null,
  fk1  NUMBER(12),
  info VARCHAR2(50)
alter table TEST2
  add constraint PK_TEST2 primary key (ID2);
alter table TEST2
  add constraint FK_TEST2_TO_TEST1 foreign key (FK1)
  references TEST1 (ID);
-- and here is the code when I add on delete cascade for FK
alter table TEST2
  drop constraint FK_TEST2_TO_TEST1;
alter table TEST2
  add constraint FK_TEST2_TO_TEST1 foreign key (FK1)
  references TEST1 (ID) on delete cascade;