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2012-04-04 01:20:03
IS410 Chap4 Exam Note

Chap 4,5 Exam Review
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  1. subtype
    a subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroupings
  2. supertype
    a generic entity type that has a relationship with one or more subtype
  3. attribute inheritance
    a property by which subtype entities inherit values of all attributes and instances of all relationships of the supertype
  4. generalization
    the process of defining a more general entity type from a set of more specialized entity types
  5. specialization
    the process of defining one or more subtypes of the supertype and forming supertype/subtype relationships
  6. completeness constraint
    a type of contraint that addresses the question whether an instance of a supertype must also be a member of at least one subtype
  7. total specialization rule
    specifies that each entity instance of the supertype must be a member of some subtype in the relationship
  8. partial specialization rule
    specifies that an entity instance of the supertype is allowed not to belong to any subtype
  9. disjointness constaint
    a constraint that addresses the question whether an instance of a supertype may simultaneously be a member of two(or more subtypes)
  10. disjoint rule
    a rule that specifies that an instance of a supertype may not simultaneously be a member of two(or more) subtypes
  11. overlap rule
    a rule that specifies that an instance of a supertype may simultaneously be a member of a member of two(or more) subtypes
  12. subtype discriminator
    an attribute of the supertype whose values determine the target subtype or subtypes
  13. -supertype/subtype hierarchy
    -a hierarchical arrangement of supertypes and subtypes, where each subtype has only one supertype
  14. entity cluster
    a set of one or more entity types and associated relationships grouped into a single abstract entity type
  15. -universal data model
    -a generic or template data model that can be reused as a starting point for a data modeling project
  16. business rules
    statements that define or constrain some aspect of the business
  17. derivation
    a statement derived from other knowledge in the business
  18. structural assertion
    a statement that expresses some aspect of the static structure of the organization
  19. action assertion
    a statement of a constraint or control on the actions of the organization
  20. derived fact
    a fact that is derived from business rules using an algorithm or inference
  21. anchor object
    a business rule(a fact) on which actions are limited
  22. action
    an operation, such as create, delete, update, or read, which may be performed on data objects
  23. corresponding object
    a business rule(a fact) that influences the ability to perform an action on another business rule
  24. relation
    a named two-dimensional table of data
  25. primary key
    an attribute(or combination of attributes) that uniquely identifies each row in a relation
  26. composite key
    a primary key that consists of more than one attribute
  27. foreign key
    an attribute in a relation that serves as the primary key of another relation in the same database
  28. null
    a value that may be assigned to an attribute when no other value applies or when the applicable valus is unknown
  29. entity integrity rule
    no primary ke attribute(or component of a composite primary key) may be null
  30. referential integrity constraint
    a rule that states that either foreign key value must match a primary key value in another relation or the foreign key value must be null
  31. well-structured relation
    a relation that contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies
  32. anomaly
    an error or inconsistency that may result when a user attempts to update a table that contains redundant date. three types of anomalies are insertion, deletion, and modification
  33. surrogate primary key
    a serial number or other system assigned primary key for a relation
  34. recursive foreign key
    a foriegn key in a relation that references the primary key values of that same relation
  35. normalization
    the process of decomposing relations with anomalies to produce smaller, well- structured relations
  36. normal form
    a state of a relation that results from applying simple rules regarding functional dependencies for relationships between attributes to that relation
  37. functional dependency
    a constraint between two attributes in which the value of one attributes is determined by the value of another attribute
  38. determinant
    the attribute on the left-hand side of the arrow in a functional dependency
  39. candidate key
    an attribute, or combination of attributes, that uniquely identifies a row in a relation
  40. first normal form(1NF)
    a relation that has a primary key and in which there are no repeating groups
  41. second normal form(2NF)
    a relation in first normal form in which every nonkey attribute is fully functionally dependent on the primary key
  42. partial functional dependency
    a functional dependency in which one or more nonkey attributes aare functionally dependent on part(but not all) of the primary key
  43. third normal form(3NF)
    a relation that is in second normal form and has no transitive dependencies
  44. transitive dependency
    a functional dependency between two(or more) nonkey attributes
  45. transforming EER diagrams to relations
    7 mapping relationship
    • (1)-Mapping Regular Entities to Relations
    • (2)-Mapping Binary Relationships
    • -(One-to-Many, Many-to-Many, One-to-one)
    • (3)-Mapping Weak Entities
    • (4)-Mapping Associative Entities
    • (5)-Mapping Unary Relationships
    • (6)-Mapping Ternary (and n-ary) Relationships
    • (7)-Mapping Supertype/Subtype Relationships
  46. 3 classification of business rules
    • Derivation
    • Structural assertion
    • Action assertion