Multiple Parents For One Foreign Key

Hi,

I am trying to figure out if this is possible in Oracle or Mysql

Lets say I have 3 tables such that C could have either A or B as its parent.

A
{ id, name}

B
{id, name}

C
{other_id, comment}

Now other_id could be either A.id or B.id. What I want to be able to do is to define a foreign key constraint of the type:

CONSTRAINT FK_C FOREIGN KEY (other_id) REFERENCES A(id) ON DELETE CASCADE,
CONSTRAINT FK_C FOREIGN KEY (other_id) REFERENCES B(id) ON DELETE CASCADE

such that deleting A.id automatically deletes C.other_id where A.id = C.otherid and same for B.id

Ofcourse i am not able to do this. Is there any way that this can be done in Oracle and Mysql?

Thanks a lot,
Priyanka