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Home -> Community -> Usenet -> comp.databases.theory -> Re: Does Codd's view of a relational database differ from that of Date & Darwin? [M.Gittens]

Re: Does Codd's view of a relational database differ from that of Date & Darwin? [M.Gittens]

From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 10 Jun 2005 10:30:11 -0700
Message-ID: <1118424611.015262.80150@g47g2000cwa.googlegroups.com> 





My comment on this thread would be that the problems here
arise not from missing information per se, nor from the empty
set, special values, or whatever. The problems arise from
3VL. Once you introduce an unknown value, you can't
say anything about anything. Is x = UNKNOWN? It might
be, it might not; you can't tell. What about the sum of a set
of numbers and an UNKNOWN? Nothing can be said about it.




Marshall
Received on Fri Jun 10 2005 - 12:30:11 CDT












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