CSC 742 Database Management Systems Phases ... - Dr. Peng Ning
CSC 742 Database Management Systems Phases ... - Dr. Peng Ning
CSC 742 Database Management Systems Phases ... - Dr. Peng Ning
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Classification<br />
Predicate-based: when a defining predicate<br />
determines the subclass of which a given<br />
instance is member<br />
Attributed-based: when the predicate<br />
applies only on an attribute<br />
User-defined: when the user decide the<br />
subclass membership<br />
Disjoint vs. overlapping<br />
Total vs. partial<br />
Spring 2002 <strong>CSC</strong> <strong>742</strong>: DBMS by <strong>Dr</strong>. <strong>Peng</strong> <strong>Ning</strong> 27<br />
Constraints on<br />
Specialization/Generalization<br />
Disjointness constraint<br />
The subclasses of the specialization must<br />
be disjoint.<br />
Specified by (d)<br />
Otherwise, the subclasses may overlap.<br />
Specified by (o)<br />
Spring 2002 <strong>CSC</strong> <strong>742</strong>: DBMS by <strong>Dr</strong>. <strong>Peng</strong> <strong>Ning</strong> 28<br />
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