Creating a many-to-many relation

[Hugo Palma-4]

Hi,
i would like to create a many-to-many relation between to entities but i
can't find any information or example on how to do this.

For example, let's say i have the following entities:

<entity entity-name="A">
<field name="ida" type="id"/>
<prim-key field="ida"/>
</entity>

<entity entity-name="B">
<field name="idb" type="id"/>
<prim-key field="idb"/>
</entity>

How can i model a many-to-many relationship between these two entities ?

Thanks in advance,
Hugo

[Malin Nicolas]

Hello Hugo,

You just create an associate class ABAssoc that contains only A pk and B pk

Nicolas

Le 30/06/2010 17:37, Hugo Palma a écrit :

> Hi,
> i would like to create a many-to-many relation between to entities but i
> can't find any information or example on how to do this.
>
> For example, let's say i have the following entities:
>
> <entity entity-name="A">
> <field name="ida" type="id"/>
> <prim-key field="ida"/>
> </entity>
>
> <entity entity-name="B">
> <field name="idb" type="id"/>
> <prim-key field="idb"/>
> </entity>
>
> How can i model a many-to-many relationship between these two entities ?
>
> Thanks in advance,
> Hugo
>
>    

--
Nicolas MALIN
Consultant
Tél : [phone]
Site projet : http://www.neogia.org/
-------
Société LibrenBerry
Tél : [phone]
Site : http://www.librenberry.net/

[David E. Jones-2]

I think what Nicolas is trying to say is that in a physical model for a relational database there is no such thing as a many-to-many relationship between tables, so you need a "join" table to implement that conceptual model.

In OFBiz you'll see a lot of these sorts of entities with a suffix of "Assoc" or "Appl" or sometimes other or no suffix, but you can find examples with those suffixes.

-David


On Jun 30, 2010, at 10:11 AM, Nicolas Malin wrote:

> Hello Hugo,
>
> You just create an associate class ABAssoc that contains only A pk and B pk
>
> Nicolas
>
> Le 30/06/2010 17:37, Hugo Palma a écrit :
>> Hi,
>> i would like to create a many-to-many relation between to entities but i
>> can't find any information or example on how to do this.
>>
>> For example, let's say i have the following entities:
>>
>> <entity entity-name="A">
>> <field name="ida" type="id"/>
>> <prim-key field="ida"/>
>> </entity>
>>
>> <entity entity-name="B">
>> <field name="idb" type="id"/>
>> <prim-key field="idb"/>
>> </entity>
>>
>> How can i model a many-to-many relationship between these two entities ?
>>
>> Thanks in advance,
>> Hugo
>>
>>  
>
>
> --
> Nicolas MALIN
> Consultant
> Tél : [phone]
> Site projet : http://www.neogia.org/
> -------
> Société LibrenBerry
> Tél : [phone]
> Site : http://www.librenberry.net/
>

[Hugo Palma-4]

Thanks Nicolas and David. Got it working.

Cheers,
Hugo

On Wed, Jun 30, 2010 at 17:24, David E Jones <[hidden email]> wrote:

>
> I think what Nicolas is trying to say is that in a physical model for a
> relational database there is no such thing as a many-to-many relationship
> between tables, so you need a "join" table to implement that conceptual
> model.
>
> In OFBiz you'll see a lot of these sorts of entities with a suffix of
> "Assoc" or "Appl" or sometimes other or no suffix, but you can find examples
> with those suffixes.
>
> -David
>
>
> On Jun 30, 2010, at 10:11 AM, Nicolas Malin wrote:
>
> > Hello Hugo,
> >
> > You just create an associate class ABAssoc that contains only A pk and B
> pk
> >
> > Nicolas
> >
> > Le 30/06/2010 17:37, Hugo Palma a écrit :
> >> Hi,
> >> i would like to create a many-to-many relation between to entities but i
> >> can't find any information or example on how to do this.
> >>
> >> For example, let's say i have the following entities:
> >>
> >> <entity entity-name="A">
> >> <field name="ida" type="id"/>
> >> <prim-key field="ida"/>
> >> </entity>
> >>
> >> <entity entity-name="B">
> >> <field name="idb" type="id"/>
> >> <prim-key field="idb"/>
> >> </entity>
> >>
> >> How can i model a many-to-many relationship between these two entities ?
> >>
> >> Thanks in advance,
> >> Hugo
> >>
> >>
> >
> >
> > --
> > Nicolas MALIN
> > Consultant
> > Tél : [phone]
> > Site projet : http://www.neogia.org/
> > -------
> > Société LibrenBerry
> > Tél : [phone]
> > Site : http://www.librenberry.net/
> >
>
>