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Namespace: WIN_COM_API
The following definitions apply to the context of Data Modeling (or something other than "implemented relation(?)". Work with me, Jim.)


A key is not a unique value. Primary Key and Candidate Key are unique values. A Key can refer to primary, foreign, candidate, or alternate keys.

A Natural Key can still be used even it is not the Primary Key. A Natural Key can be system generated, for example an Invoice number versus an Invoice ID Surrogate Key.

I find the easiest way to recognize a Natural Key is to ask, "Would this still be part of the record if it were not being used as the Primary Key?" If the answer is yes then it is a Natural Key otherwise it is a Surrogate Key.

I think people should use "key" when refering to the data that links records together, and "ID" for the data that humans use to identify something.

Contributors: Carl Karsten
See Also: Set Relation Field Name Collisions
Category Data Modeling Category Exam 70-155 Hot Topic
( Topic last updated: 2006.10.11 12:20:54 PM )