Hi Ari,I hope this doesn't confuse things more, but in reality, you often have schema that fall into multiple categories of mapping.
For example, a hierarchy might have a table that maps all of the fields of the superclass A. Class B extends A and has a table BS containing a discriminator column WHICHB and the fields of all of the subclasses of B. Another class C extends A and its table C maps only the fields of class C while subclasses C1 and C2 each have their own table for their fields.
To make it easier on the ORM, table A might also include a discriminator column WHICHA that explicitly identifies the class that the row corresponds to.
Craig On Jun 2, 2007, at 3:53 PM, Aristedes Maniatis wrote:
On 03/06/2007, at 3:25 AM, Kevin Menard wrote:I think what you may have missed is that it's a single table-per-class-hierarchy, not table-per-class.Yes, you are right. I read it as (table-per-class)-hierarchy rather than table-per-(class-hierarchy).I've made a little translation table for the docs to help users coming from Hibernate/WO/JPA. Personally I far prefer the vertical/ horizontal/single-table naming since it is nicely evocative of the diagram.Ari --------------------------> Aristedes Maniatis phone +61 2 9660 9700 PGP fingerprint 08 57 20 4B 80 69 59 E2 A9 BF 2D 48 C2 20 0C C8
Craig Russell Architect, Sun Java Enterprise System http://java.sun.com/products/jdo 408 276-5638 mailto:[EMAIL PROTECTED] P.S. A good JDO? O, Gasp!
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