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Foreign key constrain

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catcat

Post subject: Foreign key constrain

Posted: Mon Jan 26, 2004 6:00 am

Beginner

Joined: Fri Jan 02, 2004 3:27 am
Posts: 23
Location: Hong Kong

During one-to-many relation. (e.g Order -> Item ). Is there any way to declare such relation in hibernate xml file such that Order is not allowed to be deleted unless there is no items associated ?

Or the foreign key constrain is not a good suitable approach?

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michael

Post subject:

Posted: Mon Jan 26, 2004 6:25 am

Hibernate Team

Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany

If I am not misstaken, the foreign key constraint should allready be generated by hbm2ddl. Or do you mean something else?

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catcat

Post subject:

Posted: Mon Jan 26, 2004 10:57 pm

Beginner

Joined: Fri Jan 02, 2004 3:27 am
Posts: 23
Location: Hong Kong

I am using MySql 4.0.15-max-nt in Windows XP.

When I create the mapping many-to-one association from Order -> Item
I want it is not allowed to execute ( eg. throw an exception )

Code:

session.delete(order) // remove the order by hibernate API

when Order have one or more Item.

Currently, I can delete the Order even there is Item assoicaite with it.

Code:

// xml in Item

<many-to-one name="purchaseOrder"
  class="hibernate.PurchaseOrder"
  cascade="none"
  outer-join="auto"
  update="true"
  insert="true"
  column="purchaseOrder"/>

Code:

// xml in Order

<bag name="purchaseItems"
  lazy="false"
  inverse="false"
  cascade="none">
    <key column="purchaseOrder"/>
    <one-to-many class="hibernate.PurchaseItem"/>
</bag>

The xml is genereted by Xdoclet

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catcat

Post subject:

Posted: Mon Jan 26, 2004 11:04 pm

Beginner

Joined: Fri Jan 02, 2004 3:27 am
Posts: 23
Location: Hong Kong

The following is the SQL generated from Hibernate.

Code:

create table Item (
   internalId BIGINT NOT NULL AUTO_INCREMENT,
   pOrder BIGINT,
   primary key (internalId)
)
create table POrder (
   pId BIGINT NOT NULL AUTO_INCREMENT,
   primary key (pId)
)

alter table Item add index (pOrder), add constraint FK9BDADFD4B0358ACD foreign key (pOrder) references POrder (pId)

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catcat

Post subject:

Posted: Mon Jan 26, 2004 11:15 pm

Beginner

Joined: Fri Jan 02, 2004 3:27 am
Posts: 23
Location: Hong Kong

Sorry, the above SQL 's variable does not match the xml provided. The item should be purchaseItem and POrder should be purchaseOrder. They are extracted from part of the code and I have rename some of the varible to make it better understanding.

Anyway, am I got something wrong in the hbm2ddl ?

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