Database Systems: Foreign Keys and Data Redundancy
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Database Systems: Foreign Keys and Data Redundancy

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Questions and Answers

What is an attribute B said to be if all rows in a table that agree in value for A also agree in value for B?

  • Partially dependent on A
  • Totally independent of A
  • Functionally dependent on A (correct)
  • Superkey dependent on A

    • What type of key is composed of more than one attribute?

  • Candidate key
  • Primary key
  • Composite key (correct)
  • Superkey

    • What is the purpose of controlled redundancy in a relational database?

  • To enable tables to be linked together (correct)
  • To reduce data entry errors
  • To increase data redundancy
  • To create logical problems in relational tables

    • What does a foreign key (FK) contain in a related table?

    <p>A primary key value</p> Signup and view all the answers

    What is the problem with nulls in a relational database?

    <p>They can create logical problems when tables are linked</p> Signup and view all the answers

    What is the purpose of entity integrity in a relational database?

    <p>To ensure each row has a unique identity</p> Signup and view all the answers

    What type of key is a superkey without unnecessary attributes?

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

    What is the purpose of referential integrity in a relational database?

    <p>To enable tables to be linked together</p> Signup and view all the answers

    What is the problem with unnecessary duplication of attribute values?

    <p>It can create logical problems when tables are linked</p> Signup and view all the answers

    What is the purpose of a primary key in a relational database?

    <p>To ensure each row has a unique identity</p> Signup and view all the answers

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