Lets say in an entity you have a field thats another entity.
Basically a join.
In the entity if you supply cascade=CascadeType.DELETE implying that deletes will be cascaded which under some scenarios may be a good idea in some cases if used carefully.

The same thing can also be done at the database level itself. When defining the Foreign key one can specify that it will cascade to delete.

If we have both what will really happen?
Will the related entities already have been deleted by the database by the time hibernate go around to deleting it?

In case it is not specified at the database and specified only using hibernate is that not too much work at the java layer for what is automatic if implemented at the database layer using the appropriate cascade when defining the foreign key.