RELATIONAL DATABASES

• RELATIONAL DATABASES RELY ON KEYS TO ESTABLISH ADDRESSING
  • PREVENTS APPLICATION PROGRAMS FROM GAINING ACCESS TO COMPUTER'S MEMORY HIERARCHY

• KEY BASED ADDRESSING CAN NOT BE USED FOR PARTIALLY DEFINED ABSTRACTIONS
  • UNDEFINED ATTRIBUTES: UNDEFINED KEYS: NULL KEYS

  • RDBMS KEY VERIFICATION ALGORITHMS DO NOT ALLOW NULL KEYS

• I.E. CAD SYSTEMS BASED ON RDBMSs REQUIRE THAT ALL DB ENTITIES BE FULLY SPECIFIED IN ORDER TO WORK

• THAT IS THE DB HAS TO CORRESPOND TO A FINISHED DESIGN

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Ugo O. Gagliardi
GSD-2317 Spring 2005-2006