Well I guess that's a resounding "Yep, you don't get it..." :)
Can you describe an instance when this would be necessary? I have read the
document, but still don't think I could put this to use productively.
Thanks again...
>From: John McNally <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: [EMAIL PROTECTED]
>Subject: Re: Inheritance in Torque/Peers
>Date: Wed, 19 Sep 2001 15:09:49 -0700
>
>Torque supports only the one table per class hierarchy style of o-r
>mapping. The <inheritance> tag is an element of <column> not <table>.
>It marks the column as distinguishing the different classes that are
>stored within the table. Leaving the extends attribute out will have
>the class extend the highest level class, the extends attribute can lead
>to a deeper hierarchy.
>
>Jonathan Porterfield wrote:
> >
> > I'm not sure I totally get this, so can someone please check my
> > understanding of the usage from my example below?
> >
> > Would this be the correct way to define inheritance between a base user
> > table and an authors table in the database definition...
> >
> > Where the two tables have the following definition.
> > ------------ ------------
> > | USERS |---o-| AUTHORS |
> > ------------- ------------
> >
> > <app-data>
> >
> > <database name=MyData>
> >
> > <table name="USERS" idMethod="idbroker">
> > <column name="USERID" inheritance="single" type="INTEGER" size="4"
> > primaryKey="true"/>
> > <inheritance key="AUTHORS" class="AUTHORS"
> > extends="com.mycompany.project.om.USERS"/>
> > <column name="USER_NAME" type="VARCHAR" size="255" />
> > </table>
> >
> > <table name="AUTHORS" idMethod="idbroker" >
> > <column name="AUTHORID" type="INTEGER" size="4" primaryKey="true"
> > required="true"/>
> > <column name="USERID" type="INTEGER" size="4" />
> > <column name="AUTHOR_BIO" type="VARCHAR" size="255"/>
> > <foreign-key foreighTable="USERS">
> > <reference foreign= local=>
> > </foreign-key>
> > </table>
> >
> > </database>
> >
> > </app-data>
> > ------------------
> > Here, AUTHORS extends USERS so...
> > 1) Criteria crit = new Criteria();
> > AuthorsPeer.doSelect(crit);
> >
> > should fetch
> > - USERID, USER_NAME, AUTHORID, AUTHOR_BIO
> >
> > (T/F)?
> >
> > 2) And by the same token, and although it would be unconventional, it
>would
> > be possible to use
> > Criteria crit = new Criteria();
> > crit.add (AuthorsPeer.UserName,"Ralph Malph");
> > Object o = CategoryPeer.doInsert (crit);
> >
> > to add a "Ralph Malph" user to the USERS table
> > (T/F)?
> >
> > 3) Will this also create a row in the AUTHORS table?
> >
> > 4) Question - If inheritance is defined, is foreign-key definition
>redundant
> > to the point of uselessness?
> >
> > 5) I see in the DTD that the attribute "extends" of the element
> > "inheritance" is optional (#IMPLIED).
> > What would be the effect of removing the extends attribute from the
> > inheritance attribute in the example above?
> >
> > Thanks in advance for any response
> > -Cheers
> >
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