Delete a child and a parent row with one SQL script

Question

Instead of deleting the child row and then writing another sql statement to delete the parent row I wanted to use one statement which will do both. FYI: we use Oracle databa

Answer 1

You can only do it badly - i.e., using triggers.

create table parent
(pid number,
   constraint parent_pk
     primary key (pid)
     using index
);

create table child
  (cid number,
   pid number,
   constraint child_pk
     primary key(cid)
     using index,
   constraint child_fk
     foreign key (pid)
     references parent (pid)
  );

create index child_fk on child (pid);

create trigger fake_delete_cascade
before delete on parent
for each row
begin
  delete from child where pid = :old.pid;
end;
/

insert into parent values (1);
insert into child values (1,1);
commit;
select count(*) from child;
delete from parent where pid = 1;
select count(*) from child;