Richard Warr (4/27/2011)
Nice question and an interesting example. Would renaming the columns "Telephone 1" and "Telephone 2" to "Home Phone" and "Mobile Phone" mean that the table was then in 1NF?
Great thought. It's funny how even a definition of something so basic, like 1NF, can still be fuzzy. If you're going by Chris Date's definition, his fourth rule states "Every row-and-column intersection contains exactly one value from the applicable domain (and nothing else)." Now, are all categories of telephone numbers (mobile, home, work etc.) considered of the same "domain"? Not to mention, adding a second telephone number field would mean one of them could possibly be null. Null fields, to some, is also a violation of 1NF.
... I think it's a trick question and I want extra points!
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