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The Business Rules have been drafted.
  • A Physical Data Model is shown below and An Access Database is available on request.

    DESIGN NOTES :-
    The design is very simple.
    Unfortunately, writing the SQL to display Hierarchies is not so simple, UNLESS you are using Oracle.
    Oracle has provided a 'CONNECT BY' extension to ANSI-standard SQL that handles hierarchies very easily.
    A neat demonstration can be seen which uses a powerful product called Dynamic PL/SQL.

    Details for Oracle are shown on our Business Rules page for this Data Model.
    However, for SQL Server and DB2 the SQL to retrieve a hierarchy is not so simple.
    The best approach is to define an underlying Table with a generic design for hierarchies, and then use SQL Views to retrieve the data and define the layout for display.
    Joe Celko has a discussion in Chapter 26 on 'Trees' in his book 'SQL for Smarties' (5 Stars on Amazon).


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