Re: Cascade Deletes

I guess it all depends on the application. I believe that cascade deletes are very useful in particular situations because it is a sure fire way of getting rid of all related records. There is one problem that I can see though. If you had a table, lets just say and employee table for and example. This employee table has SSN numbers as a primary key. Also in this table you have the SSN number of that employees supervisor. The supervisor is a foreign key to the primary key (employee SSN). Now, if you had a cascade delete on the foreign key, and lets say you wanted to delete an SSN from the table, you would wipe out records that had that SSN for the supervisor. In this case you would not want to use a CASCADE, instead you might use a SET NULL ON DELETE, so that the supervisor field gets set to null instead of deleting the employee. It is all kind of hard to explain in words, but I could maybe see why they don't want to use it. Depending on the complexity, you could inadversly reek havoc on your database because these deletes are behind the scene.

good luck
kevin

Manoj Goel wrote:

> hi Guys,
>
> I have been asked to not to use cascade deletes in our app which is
> running on
> oracle 7.3 . But I thought that if it is an option provided by the RDBMS
> then why
> not use it ?
>
> What could be disadvantages??
>
> Please help me understand it.
>
> Thanks
>
> Manoj

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The opinions expressed in this message are purely my own and NOT those of my company.