从一个表到另一个表中的单个主键有多个外键是否可以？

Question

Say I have two tables

Products table:

|ProductID|ProductName|ListPrice|

PrebuiltSystems table:

|BuldID|Processor|Motherboard|RAM|

The values for the Processor, Motherboard etc. are all existing ProductID 's. I am now creating foreign key relationships from each of the part name columns to the one ProductID and have a bunch of navigation properties and relationships lines being created for each part. Is this ok?

Or is there some kind of relationship merger/rule that I can use to say all those columns are foreign keys to productID without creating one to one relationships ?

Answer 1

Is this ok?

Yes, this is the right way to do it.

Or is there somekind of relationship merger/rule that I can use to say all those columns are foreign keys to productID

No, they are all different relationships.

without creating one to one relationships ?

Note that these are many-to-one , not one-to-one relationships, many PrebuiltSystems will have the same Processor

Answer 2

Yes it is fine to have multiple foreign keys. However, in your example, I'd still do it differently; if you have one column for each component type you limit yourself very much. What do you do with a multi-CPU-system? What with multiple harddisks etc.?

You should rather normalize the PrebuiltSystems table so that you have a link table which creates a n-to-n relationship to the products (eg each product can be part of any number of prebuilt systems, and each prebuilt system can have any number of products in it).