Key Rules

[squidster]

Is it possible for a foreign key in a child table to be a secondary key from the parent table instead of the primary key?
How would this affect referential integritty , if at all?

This is based on the definition that the secondary key is an attribute that will uniquely identify the parent entity record.

This is required really to aid data input as the secondary key will have more meaning to the user.

Hope this makes sense

 

[SemperFiDownUnda]

A foriegn key can be any unique column in the parent table. It need not be the primary key.

 

[squidster]

Thanks, I kinda thought so but books I'm reading don't actually say so unambiguously. They allways tend to say a foreign key must relate to a primary key in the parent table.

Tahnks again