EJB 3 CascadeType annotation not required? if specified on DB.

Hi All,

If I using on delete/update cascade on my DB , then is it required for me to use annotation at the entity level ? And if not used what will be the result?

Whenever a entity manager remove/update is called entity , finally the request goes to DB and DB performs the cascade operations if any. But if that's the case then I am not able to understand why CacadeType annotation are introduced?