INTEGRITY CONSTRAINTS

• BESIDES THE INTEGRITY CONSTRAINS DISCUSSED FOR THE RELATIONAL MODEL THE FOLLOWING ARE SPECIFIC TO ODBMSs:
  
  
  • MIGRATION OF OBJECTS BETWEEN CLASSES: APPLICABLE TO SYSTEMS WHICH ALLOW OBJECTS TO MODIFY THEIR OWN CLASS
    
    
    • EX: AN OBJECT OF CLASS CHICKEN CAN NOT BE ALLOWED TO BECOME AN INSTANCE OF CLASS EGG
    
    
  • EXCLUSIVITY BETWEEN CLASSES: APPLICABLE TO SYSTEMS THAT ALLOW OBJECTS TO BE INSTANCES OF SEVERAL CLASSES
    
    
    • EX: THE EXTENTS OF CLASS C1 & C2 MUST BE DISJOINT
    
    
  • ON THE DEFINITION OF SUBCLASSES
    
    
    • EX: CERTAIN INHERITED METHODS & ATTRIBUTES CANNOT BE REDEFINED
    
    
  
  

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Lect3_2004: Copyright U. O. Gagliardi 1994-2004

Ugo O. Gagliardi
GSD-6306 Spring 2003-2004