DB 2

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  1. EER Diagram
    An enhanced ER diagram, which is basically an ER diagram that also shows subtypes and supertypes of entities and identifies the realtionships between them
  2. Both sub types and super types
    Have to be necessary to the organization
  3. An entity type that includes distinct subtypes that needs to be represented in the data model
  4. 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
  5. All subtypes ________ of the attributes from the supertype
    inherit all
  6. Each subtypes has other ________ attributes
  7. The process of minimizing the differences between entities by identifying their common features
    Generalization, a bottom up approach
  8. The process of maximizing the differences between members of an entity by identifying their distinguishing characteristics
    specialization, a top down approach
  9. An attribute of the supertype whose values determine the target subtype or subtypes
    Subtype discriminator
  10. Participation constraints
    • Dictate whether every member of a superclass must participate as a member of a subclass
    • Total or partial particiaption
  11. Disjoint constraints
    • Define whether it is possible for an instance of a superclass to be a member of one or more subclasses simultaneously
    • Disjoint or overlap
  12. The constraint that specifies that an entity can be a member of only of the subtypes of the specialization
    Disjoint rule
  13. An entity can be a member of more than one subtype of specialization
    overlap rule
  14. Image Upload
    • Total specialization
    • Every instance of the supertype has to belong to one of the subtypes
  15. Image Upload
    Partial specialization, every entity in the supertype need not belong to any of the subtypes in the speicalization
  16. The 3 component of a relational data model
    • Relational data structure - how to store the data
    • Data manipulation - how to manipulate the data
    • Relational Data integrity - how to maintain integrity
  17. Two dimensional grid that holds data about the object, main data structure used
    • Relational
    • -STUDENT(SSN, Name, Email, DeptNAme)
  18. Examples of data manipulation
  19. Two main types of database integrity constraints
    • Entity integrity
    • Referential (Reference) integrity
  20. a minimal (irreducible) superkey
    Candidate key
  21. A candidate key selected to be used as the primary row indentifier
    Primary key
  22. Attribute (or attributes) used for data retrieval
    secondary key
  23. Entity integrity implies that
    • Every relation in a reltional data model has a unique primary key
    • The data values for all attributes in teh primary key are not null
  24. Referential integrity implies that
    Every non NULL foreign key references an existing primary key value
  25. What do ER diagrams capture that individual relations do not
  26. Image Upload
    Simple attribute - map directly into the relation
  27. Image Upload
    Composite attribute - use only their component attributes,
  28. Image Upload
    Multivalues attribute, becomes a separate relation with a foreign key taken from the superior entity
  29. Mapping a one to many relationship
    Relationship in which the primary key on the one side becomes the foreign key on the other side
  30. Mapping one to one realtionship
    • Primary key on mandatory side becomes foreign key on optional side
    • Never going to copy both ways
  31. Mapping many to many
    • Create a new relation with the primary keys of the two entities as it's primary key
    • You always have an associative entity
  32. Associative entity always has
    The primary keys of the entities being associated by it
  33. Mapping many to many for unary tables
    two relations, one for the entity type and one for an associative relation in which the primary key has two attributes, both taken from the primary key of the original entity type
Card Set:
DB 2
2016-09-21 16:33:51

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