Database Management Systems: Keys and Attributes
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Questions and Answers

What is an attribute that can be calculated from other attributes?

  • Derived attribute (correct)
  • Key attribute
  • Composite attribute
  • Multi-valued attribute

    • What is the minimal set of attributes that uniquely identifies an entity in the entity list?

  • Super key
  • Composite key
  • Key attribute (correct)
  • Primary key

    • What is a single candidate key designated as in a single entity?

  • Key attribute
  • Composite key
  • Primary key (correct)
  • Super key

    • What is an example of a derived attribute in an employee entity?

    <p>Employee age</p> Signup and view all the answers

    What are the attributes that contain multiple values called?

    <p>Multi-valued attributes</p> Signup and view all the answers

    What is a characteristic of a weak entity type?

    <p>It cannot exist without a related entity</p> Signup and view all the answers

    What can be multiple in a single entity, according to the entity list?

    <p>Candidate keys</p> Signup and view all the answers

    What are the attributes in the weak entity that participate in the primary key called?

    <p>Partial keys</p> Signup and view all the answers

    What is the cardinality of the identifying relationship between the owner entity and the weak entity?

    <p>One-to-one or one-to-many</p> Signup and view all the answers

    What is the relationship between the owner entity and the weak entity called?

    <p>Identifying relationship</p> Signup and view all the answers

    What is a requirement for a weak entity in the identifying relationship?

    <p>It must have a total participation</p> Signup and view all the answers

    What is a composite key composed of?

    <p>A group of attributes that make up the key</p> Signup and view all the answers

    What is the primary key of a relation?

    <p>A minimal set of attributes that uniquely identify a relation</p> Signup and view all the answers

    What is a super key?

    <p>Any set of attributes that uniquely identify a relation</p> Signup and view all the answers

    What is the difference between a primary key and a super key?

    <p>A primary key is a minimal set of attributes, while a super key is any set of attributes</p> Signup and view all the answers

    What is an example of a composite key?

    <p>(cust_id, product_code)</p> Signup and view all the answers

    What is the purpose of a key in a relation?

    <p>To identify a specific row in a table</p> Signup and view all the answers

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