Chapter 3.txt

  1. Business Rule -
    A statement that defines or constrains some aspect of the business. It is intended to asset business structure or to control or influence.
  2. Entity-relationship diagram -
    (E-R diagram) A detailed, logical, and graphical representation of the entities, associations, and data elements for an organization or business area.
  3. Cardinality -
    The number of instances of entity B that can (or must) be associated with each instance of entity A.
  4. Associative entity:
    • An entity type that associates the
    • instances of one or more entity types and contains
    • attributes that are peculiar to the relationship
    • between those entity instances. (3)
  5. Attribute:
    • A property or characteristic of an entity or relationship
    • type that is of interest to the organization. (3)
  6. Binary relationship:
    • A relationship between the instances
    • of two entity types. (3
  7. Composite attribute:
    • An attribute that has meaningful component
    • parts (attributes). (3)
  8. Composite identifier:
    • An identifier that consists of a composite
    • attribute. (3)
  9. Degree:
    • The number of entity types that participate in a
    • relationship. (3)
  10. Derived attribute:
    • An attribute whose values can be
    • calculated from related attribute values. (3)
  11. Entity type:
    • A collection of entities that share common
    • properties or characteristics. (3)
  12. Entity-relationship diagram (E-R diagram or ERD):
    • A graphical representation of an entity-relationship
    • model. (3)
  13. Entity-relationship model (E-R model):
    • A logical representation
    • of the data for an organization or for a business area
    • using entities for categories of data
  14. Fact:
    An association between two or more terms. (3)
  15. Identifier:
    • An attribute (or combination of attributes)
    • whose value distinguishes instances of an entity
    • type. (3)
  16. Identifying owner (owner):
    • The entity type on which the
    • weak entity type depends. (3)
  17. Identifying relationship:
    • The relationship between a weak
    • entity type and its owner. (3)
  18. Multivalued attribute:
    • An attribute that may take on more
    • than one value for a given entity (or relationship)
    • instance. (3)
  19. Optional attribute: An attribute that may not have a value
    • for every entity (or relationship) instance with which
    • it is associated. (3)
  20. Relationship instance:
    • An association between (or among)
    • entity instances where each relationship instance
    • associates exactly one entity instance from each participating
    • entity type. (3)
  21. Relationship type:
    • A meaningful association between (or
    • among) entity types. (3)
  22. Required attribute:
    • An attribute that must have a value for
    • every entity (or relationship) instance with which it is
    • associated. (3)
  23. Simple (or atomic) attribute:
    • An attribute that cannot be
    • broken down into smaller components that are meaningful
    • to the organization. (3)
  24. Strong entity type:
    • An entity that exists independently of
    • other entity types. (3)
  25. Term:
    • A word or phrase that has a specific meaning for the
    • business. (3)
  26. Ternary relationship:
    • A simultaneous relationship among
    • the instances of three entity types. (3)
  27. Time stamp:
    • A time value that is associated with a data
    • value, often indicating when some event occurred
    • that affected the data value. (3)
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Chapter 3.txt
DB Glossary