Re: 3 way Many to many
Re: 3 way Many to many
- Subject: Re: 3 way Many to many
- From: Art Isbell <email@hidden>
- Date: Mon, 27 Jan 2003 20:16:33 -1000
On Monday, January 27, 2003, at 06:18 AM, Jevon Hills wrote:
Here is my attempt to send an ascii ER model of what we're thinking of.
+==========+
+console +
+----------------- +
-------+consoleID +
| +==========+
|
|
|
+========================+ |
+ConsolePersonPermission + | +========= +
+------------------------------------------+ | +person +
+consoleID +---------- | +-----------------+
+personID +----------------- +personID +
+permissionID +---------- | +==========+
+========================+ |
| +=============+
| +permission +
| +----------------------+
|-------+permissionID +
+=============+
This way you can circumvent the model. You must link
People to Consoles to Permissions
all at once.
This should work fine as long as this model represents reality and you
model the relationships as EOModeler does when it creates a
many-to-many relationship between 2 entities. The to-many
relationships to the join entity must all propagate their primary keys
and they should cascade delete. It might not make sense to flatten all
relationships across the join entity unless they will all be used in
your app. Don't set relationships as class properties unless you'll be
using them.
Art
http://homepage.mac.com/aisbell/
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