DBMS 4. Entity -relationship Modeling

46 Questions | Total Attempts: 1446

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4. Entity -Relationship Modeling


Questions and Answers
  • 1. 
    ER was developed by Chen in 1980
    • A. 

      True

    • B. 

      False

  • 2. 
    ER was developed by Chen in 1976
    • A. 

      True

    • B. 

      False

  • 3. 
    ER aims to
    • A. 

      Facilitate database programming

    • B. 

      Facilitate database organization

    • C. 

      Facilitate database design

  • 4. 
    The Consceptual data model is the set of concepts that 
    • A. 

      Describe the structure of a database and the associated insert and update transactions

    • B. 

      Describe the structure of a database and the associated retrieval and update transactions

    • C. 

      Describe the structure of a database and the associated retrieval transactions

  • 5. 
    An ERs purpose is to support a users perception of the data and conceal the technical aspects associated with database design. 
    • A. 

      True

    • B. 

      False

  • 6. 
    A high level conceptual model is dependent on the DBMS and HW platform used to implement the database
    • A. 

      True

    • B. 

      False

  • 7. 
    The basic concepts of Entity-Relationship model include:
    • A. 

      Entity types

    • B. 

      File types

    • C. 

      Relationship types

    • D. 

      Atrtributes

    • E. 

      Storage detailes

  • 8. 
    Entity type = An object or concept identified by the enterprise as having an ______________ existance 
  • 9. 
    A Entity is
    • A. 

      An instance of an Entity type that is uniquely identifiable

    • B. 

      An instance of a DBA type that is uniquely identifiable

    • C. 

      An instance of a type that is uniquely identifiable

  • 10. 
    Weak entity type
    • A. 

      An entity that is not existance-dependent on some other entity type

    • B. 

      An Entity that characterizes a DBMS

    • C. 

      An instance that is existance dependent on some other entity type

  • 11. 
    Strong entity type
    • A. 

      An entity that is not existance-dependent on some other entity type

    • B. 

      An Entity that characterizes a DBMS

    • C. 

      An instance that is existance dependent on some other entity type

  • 12. 
    An Atribute is a property of an entity or a relationship type
    • A. 

      True

    • B. 

      False

  • 13. 
    An Atribute
    • A. 

      a set of values that might be asigned to an atribute

    • B. 

      is a property of an entity or a relationship type

  • 14. 
    An Atribute domain
    • A. 

      a set of values that might be asigned to an atribute

    • B. 

      is a property of an entity or a relationship type

  • 15. 
    Simple atribute
    • A. 

      An attribute that represents a value that is derivable from a related atrribute or set of atributes, not necessarily in the same entity

    • B. 

      An attribute that holds multiple values for a single component

    • C. 

      An attribute that holds a single value for a single entity

    • D. 

      An atribute composed of multiple components each with individual existance

    • E. 

      An atribute composed of a single component with an independent existance

  • 16. 
    Composite atribute
    • A. 

      An attribute that represents a value that is derivable from a related atrribute or set of atributes, not necessarily in the same entity

    • B. 

      An attribute that holds multiple values for a single component

    • C. 

      An attribute that holds a single value for a single entity

    • D. 

      An atribute composed of multiple components each with individual existance

    • E. 

      An atribute composed of a single component with an independent existance

  • 17. 
    Single valued atribute
    • A. 

      An attribute that represents a value that is derivable from a related atrribute or set of atributes, not necessarily in the same entity

    • B. 

      An attribute that holds multiple values for a single component

    • C. 

      An attribute that holds a single value for a single entity

    • D. 

      An atribute composed of multiple components each with individual existance

    • E. 

      An atribute composed of a single component with an independent existance

  • 18. 
    Multi- valued atribute
    • A. 

      An attribute that represents a value that is derivable from a related atrribute or set of atributes, not necessarily in the same entity

    • B. 

      An attribute that holds multiple values for a single component

    • C. 

      An attribute that holds a single value for a single entity

    • D. 

      An atribute composed of multiple components each with individual existance

    • E. 

      An atribute composed of a single component with an independent existance

  • 19. 
    Derived atribute
    • A. 

      An attribute that represents a value that is derivable from a related atrribute or set of atributes, not necessarily in the same entity

    • B. 

      An attribute that holds multiple values for a single component

    • C. 

      An attribute that holds a single value for a single entity

    • D. 

      An atribute composed of multiple components each with individual existance

    • E. 

      An atribute composed of a single component with an independent existance

  • 20. 
    A Candidate key is an atribute or set of atributes that uniquely identifies individual occurences of an entity type
    • A. 

      True

    • B. 

      False

  • 21. 
    The Primary key
    • A. 

      Uniquely identifies each occurance of an entity type

    • B. 

      Is equivalant with a composite key

    • C. 

      Is the candidate key selected to be a primary key

  • 22. 
    A Composite key is an candidate key that cosists of two or more atributes
    • A. 

      True

    • B. 

      False

  • 23. 
    A relationship type is a meaningless association among entity types
    • A. 

      True

    • B. 

      False

  • 24. 
    Degree of a relationship
    • A. 

      Is always 1

    • B. 

      The number of participating entities in a relationship

    • C. 

      The number of representations in a relationship

  • 25. 
    Recursive relationship 
    • A. 

      A relationship where the same entity participates more than once in different roles

    • B. 

      A relationship where the same entity participates more than once in the same roles

    • C. 

      Participates only once in different roles

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