Database Systems: Foreign Keys and Data Redundancy
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Questions and Answers

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

  • To eliminate data redundancy
  • To enhance data retrieval speed
  • To improve data storage efficiency
  • To enable tables to be linked together (correct)

What is the consequence of null values in a database when using functions such as COUNT, AVERAGE, and SUM?

  • They slow down the query execution
  • They have no impact on the results
  • They increase the accuracy of the results
  • They create logical problems (correct)

What is the characteristic of a superkey in a database table?

  • It is a subset of a composite key
  • It is a primary key without null values
  • It uniquely identifies each row (correct)
  • It is composed of multiple attributes

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

<p>To establish relationships between tables (D)</p> Signup and view all the answers

What is the consequence of unnecessary duplication of attribute values in a database?

<p>It creates redundancy (C)</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 (C)</p> Signup and view all the answers

What is the characteristic of a composite key in a database table?

<p>It is composed of more than one attribute (A)</p> Signup and view all the answers

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

<p>To ensure foreign key values match primary key values (A)</p> Signup and view all the answers

What can null values represent in a database?

<p>Any of the above, including a 'not applicable' condition (C)</p> Signup and view all the answers

What is the benefit of using keys in a relational database?

<p>It enables relationships between tables (B)</p> Signup and view all the answers

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