Foreign key mapping

elCarboner · **Joined:** Tue Sep 13, 2005 5:17 am **Posts:** 3

I have two tables:

Table1

* Pk1 (integer)
* Pk2 (integer)
* Pk3 (integer)
fk1 (integer)

and

Table2

*fk1 (integer)
*Pk5 (integer)
desc

I would map with xml descriptors the relation between table1 and table2 using fk1. Anny suggestions?

Thanks in advance for your help.

kdekooter · **Joined:** Mon Apr 12, 2004 6:33 pm **Posts:** 35

In hibernate you do not map foreign keys. In object terms there is no such thing as a foreign key.

In OR-land you map an object and its associations to other objects. I suggest you read this chapter: http://www.hibernate.org/hib_docs/v3/re ... pping.html

elCarboner · **Joined:** Tue Sep 13, 2005 5:17 am **Posts:** 3

I don´t understand what you want to say exactly...

I only need to obtain the xml that corresponds to my tables definition. I know how I can relation two tables with compound keys but not in this case.

In this example, one element of foreign key fk1 in table1 correspond to many elements on table2.

ErikFK · **Posted:** Tue Sep 13, 2005 11:38 am

elCarboner wrote:

In this example, one element of foreign key fk1 in table1 correspond to many elements on table2.

Looks like a nasty one to me. One question to clarify my thoughts:
is fk1 a unique index in Table1 or is there actually a many to many relationship between Table1 and Table2 over fk1?

Erik

elCarboner · **Joined:** Tue Sep 13, 2005 5:17 am **Posts:** 3

fk1 is a unique index on table1.

I know that is not the best form to relation this tables, but my legacy system is so fussy...

Thanks.

ErikFK · **Posted:** Tue Sep 13, 2005 1:11 pm

I would recommend something like

Code:

<class name="Table2 ...>
  <composite-id>
    <key-property name="fk1" />
    <key-property name="pk5" />
  </composite-id>
  <many-to-one class="Table1" name="table1" property-ref="fk1" column="fk1" insert="false" update="false" />
</class>

<class name="Table1">
  <...>
  <property name="fk1" unique="true" not-null="true" />
  <set name="table2s" >
    <key>
      <column name="fk1" />
    </key>
    <one-to-many class="Table1"/>
  </set> 
</class>

Note that this is only the draft of a draft...
Hope this helps anyway

Erik