Re: 1 foreign key to 2 different tables?

Use CHECK when you create the table.



Ryan Riehle wrote:

> Hi,
>
> I have a key structure like so:
>
>  a                c              b
> +----------+    +---------+    +----------+
> | PriKey1  |--->| ForKey  |<---| PriKey2  |
> |          |    | Flag    |    |          |
> +----------+    +---------+    +----------+
>
> ...where c.ForKey is a value from PriKey1 OR PriKey2, which are different
> values.  All fields have the same data type; a.PriKey1 and b.PriKey2 are
> sequences. How does one enfore referential integrity in this structure so
> that c.ForKey references a.PriKeya when Flag is True or references b.PriKey2
> when Flag is False? Looked pretty hard through the lists and on Google last
> night with no luck :(
>
>   -Ryan Riehle
>    http://www.buildways.com
>
> KEYWORDS: one foreign key, multiple primary keys, multiple tables,
> generalization, superclass, subclass, constraint
>
>
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