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3.4.12. Completeness constraint

  • Total specialisation
    • Every entity in the superclass must be a member of atleast 1 subclass
    • Double line (as ER)
  • Partial specialisation
    • Some entites may belong to atleast 1 subclass, or none at all
    • Single line
  • Yields 4 possibilities
    • (Total-Dis, Total-Over, Partial-Dis, Partial-Over)
‹ 3.4.11. Disjointness constraintup3.4.13. EER Chip example ›
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