EJB CMP 2.0 and Referential Integrity. 2004-10-31 - By Markus Fuchs
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Hi Vikram,
Having a Many To One relationship between A and B means that the foreign key
must be defined in B's table, so removing Entity B has no effect on A's
representation in the database. The EJB Spec. defines relationships to be
"managed", i.e. the container must remove Entity B from the relationship to
Entity A in memory. (See for instance EJB 2.1 Spec, sec. 10.3.7.5).
B's cascadeDelete setting or foreign keys in the database have no influence on
this behavior. The container will handle the described situation automatically.
Regards,
-- markus.
"Naik, Vikram ( eBiz Mumbai )" wrote:
> Thanks for your response.
>
> Thats, true container does take care of cascade delete, but what happens in
the following scenario:
>
> Say we have a Many to One aggregate uni-directional CMR relation between
Entity A and Entity B.
>
> Now, if we try to delete Entity B which is still be referred/ referenced by
Entity A, the container just deletes the Entity B. unless we define a foreign
key constraint at database level, that would restrict the deletion.
>
> Can container handle this stiuation, even if we dont defined foreign key
constraints at database level ?
> Is this something that developer has to take care of ?
>
>
>
> -- --Original Message-- --
> From: Guy Katz [mailto:gkatz@(protected)]
> Sent: Sun 10/31/2004 7:54 AM
> To: J2EE-INTEREST@(protected)
> Cc:
> Subject: Re: EJB CMP 2.0 and Referential Integrity.
>
>
>
> if you use CMR
> referential intergrity is a built in part of the game.
> depending on the nature of your CMR definition (multiplicity etc..)
> the container will take care of it as long as you call your CMR
methods.
>
>
> -- --Original Message-- --
> From: A mailing list for Java(tm) 2 Platform, Enterprise Edition
> [mailto:J2EE-INTEREST@(protected)]On Behalf Of Naik, Vikram ( eBiz
> Mumbai )
> Sent: Saturday, October 30, 2004 7:47 PM
> To: J2EE-INTEREST@(protected)
> Subject: EJB CMP 2.0 and Referential Integrity.
>
>
> Hello,
>
> What are the different ways to have referential integrity for your
data,
> when the persistence is done using EJB CMP 2.0 ?
>
> We are using database foreign key constraints along with CMR to
achieve the
> same ?
>
> Would appreciate all your thoughts on the above.
>
> Regards,
> Vikram.
>
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