how to descript the many to one relationship in model when there are more than 1 tables

[Holland_zwz]

Sometimes table have more than one foreign key reference to other tables. Then how to descript it in model?

For eg:

Table A:

create table A (

   oid                  varchar(10)          not null,

   pid                  varchar(10)          not null,

   color               varchar(20)          null

)

alter table A add constraint A_PK primary key (oid)

Table B:

create table B(

   oid                  varchar(10)         not null,

   pid                  varchar(10)         not null,

   name              varchar(100)        null

)

alter table B add constraint B_PK primary key (oid)

Table C:

create table  C (

   id                   varchar(10)          null,

   cid                  varchar(10)          null,

   oid                  varchar(10)          null

)

alter table  C add constraint C_FK1 foreign key (oid) references A(oid)

alter table C add constraint C_FK2 foreign key (oid)  references B(oid)

in this case, how to descript it in model?

class ModelA(models.Model):

      oid = models.CharField(max_length=10,primary_key=True)

      ...

class ModelB(models.Model):

      oid = models.CharField(max_length=10,primary_key=True)

      ...

class ModelC(models.Model):

      oid = models.ForeignKey(...) ?

[James Schneider]

You are probably looking for a many-to-many relationship using an intermediary table:

https://docs.djangoproject.com/en/1.8/topics/db/models/#intermediary-manytomany

-James

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[Holland_zwz]

Hi James,

   Thanks for reply. 

   But i am not got the main point. The problem is the table C's oid column data comes from  A or  B.  I think this is not same as many-to-many relationships.

Thanks

-hollandz

在 2015年8月6日星期四 UTC+8下午6:14:25，James Schneider写道：

[Javier Guerra Giraldez]

On Thu, Aug 6, 2015 at 8:18 AM, Holland_zwz <holla...@gmail.com> wrote:
> But i am not got the main point. The problem is the table C's oid column
> data comes from A or B.

I don't think SQL works that way. at least, it's very much against
any normalization guideline.

--
Javier