Re: [NOVICE] Conditional Relationships?

John Browne wrote:

>Ok, I'm designing a new database for work, and I have run across a
>situation where a "conditional relationship" makes sense.  Here is a
>*simplified* example of what I'm talking about:
>
>tb_address_data_us
>address_id
>addr1
>addr2
>city
>state
>zip_code
>
>tb_address_data_ca
>address_id
>addr1
>addr2
>city
>province
>postal_code
>
>tb_offices
>office_id
>manager_name
>date_opened
>
>tb_addresses_2_offices
>office_id
>country_id
>address_data_id
>
>
>As you can see, the "link" table is tb_addresses_2_offices.  This
>model makes it easy to add additional address templates in the future,
>just by adding a single data table for the new country.  But, it means
>the address_data_id can point to an id in any of the address data
>tables.  I've done some reading, and some say it's fairly common to
>see this type of model.  Others say it breaks database normalization
>rules.
>
>My question is, how often do you guys see this in "real-world"
>scenarios?  Obviously, it makes things like foreign key constraints
>difficult to use..
>
>Thoughts?
>

Okay, these address/office entries are for a company/customer/user/etc
(I'll call it a user). Can each user have multiple addresses (and
vice-versa)? Can each address have multiple offices? Once you let us
know this it will be easier to answer.

Ron