Apple

On Aug 11, 2009, at 7:05 AM, Gustavo Pizano wrote:

Hello Dave.

It does have only one parent.

Well that's good. It makes your life much easier.

What database are you using for this project? Keep in mind that WO doesn't insert objects into the database in the same order in which you may have created them, so it is entirely possible for WO to try to insert a "Sub Area" before it's "Parent Area" is inserted. Most DBs handle this situation by allowing you to defer constraints, which is handled automatically for you by the WO DB plugin. Microsoft SQLServer however does not have deferred constraints and the DB plugin doesn't handle this specific situation, so if you are using SQLServer, be careful with self-referential relationships.

Dave

On Tue, Aug 11, 2009 at 1:02 PM, David Avendasora <email@hidden> wrote:

On Aug 11, 2009, at 6:21 AM, Gustavo Pizano wrote:

Hello Im doing an eomodel.. .and I have an entity called Area, and SubArea, for me an area can have many subareas, but subarea its an area itself also..
so its like Area <- >>SubArea.

If a SubArea is really just an Area with a parent, then I'd just have one Entity of Area with an optional to-one relationship to parent.

I'd model it as Area <->> Area with Area having a foreign key that points to the PK. You'll end up with each Area having a parentArea and multiple subAreas.

This assumes that an Area can have only one parent. If an Area can have more than one parent, then you'll need a many-to-many join.

Dave

Now what are the implications of defyning Area with its properties, and then SubArea and put as parent Area?... I see that inside Area Entity there is SubArea Entity also... but I guess this doesn't guaranties me the to-many relationship between the 2 entities isn't it?do I still have t defying the relationship?

Thanks

Gustavo

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References:
	>Defining child Entities. (From: Gustavo Pizano <email@hidden>)
	>Re: Defining child Entities. (From: David Avendasora <email@hidden>)