Ved opdatering er Cascade ikke mulig i Oracle. Tom Kite siger:
There is not "on update cascade" automagically.
There are ways to do it,
o deferrable constraints. defer the foreign key check until commit, update the parent,
update the child and then commit.
Personally -- I've never found a need or use for update cascade. I'm opposed to it. If
your design requires it -- change your design now if you can.
Primary keys are supposed to be imutable, never changing, constant. It is an excessively
bad practice to have to update them ever. If there is a 0.00001% chance you will have to
update a primary key -- then it is not a primary key, its a surrogate key and you need to
find the true primary key (even if you have to make it up via a sequence)
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