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Next: Multivalued Dependencies Up: Relational Database Design Previous: Comparison of BCNF and

Normalization Using Multivalued Dependencies (not to be covered)

  1. Suppose that in our banking example, we had an alternative design including the schema:

     BC-schema = (loan#, cname, street, ccity) 

    We can see this is not BCNF, as the functional dependency

     cname  tex2html_wrap_inline1526  street ccity 

    holds on this schema, and cname is not a superkey.

  2. If we have customers who have several addresses, though, then we no longer wish to enforce this functional dependency, and the schema is in BCNF.
  3. However, we now have the repetition of information problem. For each address, we must repeat the loan numbers for a customer, and vice versa.

Osmar Zaiane
Thu Jun 18 12:56:34 PDT 1998