Database Primary Key Quiz
30 Questions
8 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which attribute is commonly used as a primary key in a database relation?

  • Department
  • Street
  • Name
  • Id (correct)

    • Why can 'Street' not be considered as a primary key?

  • It is a numerical value
  • It uniquely identifies each tuple
  • It is a common attribute
  • It can occur more than once (correct)

    • What is the role of a foreign key in a relation?

  • To calculate aggregate functions
  • To ensure uniqueness of values
  • To sort the relation
  • To reference the primary key of another relation (correct)

    • Which term is used for the relation that contains the primary key from another relation as a normal attribute?

    <p>Referenced relation</p> Signup and view all the answers

    What makes an attribute suitable to be a primary key?

    <p>Uniqueness across all tuples</p> Signup and view all the answers

    Why are attributes like 'Name' and 'Street' not ideal choices for primary keys?

    <p>'Name' and 'Street' are common attributes shared by many tuples.</p> Signup and view all the answers

    In the given SQL query, what is the missing keyword that needs to be inserted to correctly insert values into the table?

    <p>Values</p> Signup and view all the answers

    Which of the following SQL queries does not specify the relation from which the values are selected?

    <p>Select empid where empid = 1009 and lastname = ‘GELLER’;</p> Signup and view all the answers

    Which keyword is essential in an SQL query to specify the table into which values need to be inserted?

    <p>Into</p> Signup and view all the answers

    If you want to select only the 'empid' from the 'emp' table where 'lastname' is 'GELLER', which SQL query should you use?

    <p>Select empid where empid = 1009 and lastname = ‘GELLER’;</p> Signup and view all the answers

    What clause is missing in the following SQL query that causes it to be incorrect: 'Select * from empid = 10003;'?

    <p>From</p> Signup and view all the answers

    Which keyword is necessary in an SQL query to indicate the condition for selecting specific records?

    <p>Where</p> Signup and view all the answers

    To prevent cascading of authorizations from the user, which statement should be used?

    <p>Revoke select on department from Amit, Satoshi restrict</p> Signup and view all the answers

    How can confusion arising from the revoking of user roles be overcome?

    <p>The privilege must be granted only by roles</p> Signup and view all the answers

    Which keyword can be used to indicate that revocation should cascade?

    <p>Cascade</p> Signup and view all the answers

    What should be done before executing 'set role name' to associate a current role with a session?

    <p>Grant the specified role to the user</p> Signup and view all the answers

    In the context of database authorizations, what does 'revoking with restrict' prevent?

    <p>Cascading effect of revocations</p> Signup and view all the answers

    What is the purpose of granting and revoking roles by the user in a database management system?

    <p>To manage user permissions and access control</p> Signup and view all the answers

    What does the tuple relational calculus describe?

    <p>Nonprocedural query language</p> Signup and view all the answers

    In tuple relational calculus, what does the symbol ∧ represent?

    <p>Logical AND</p> Signup and view all the answers

    Which query finds the names of all instructors whose department is in the Watson building?

    <p>Finds the names of all instructors whose department is in the Watson building</p> Signup and view all the answers

    Which symbol is used in place of 'except' in relational calculus?

    <p>¬</p> Signup and view all the answers

    What does the symbol ∀ represent in SQL?

    <p>'For all' operator</p> Signup and view all the answers

    Given the sentence 'Find all students who have taken all courses offered in the Biology department', which expression matches this query?

    <p>∀ t ε r (Q(t))</p> Signup and view all the answers

    What privilege is granted in the statement 'Grant update(budget) on department to Raj'?

    <p>Update on department's budget</p> Signup and view all the answers

    How can privileges be removed from a user in a database management system?

    <p>Revoke update on employee from Amir</p> Signup and view all the answers

    Which role creation and authorization statement is correct to provide delete authorization to an instructor?

    <p>CREATE ROLE instructor; GRANT DELETE ON takes TO instructor;</p> Signup and view all the answers

    In a database management system, which statement is used to provide privilege to only a particular attribute?

    <p>Grant update(budget) on department to Raj</p> Signup and view all the answers

    What is the key aspect in creating views in a database management system?

    <p>Providing access to specific attributes only</p> Signup and view all the answers

    Which statement accurately reflects the process of removing privileges from a user?

    <p>Revoke update on employee from Amir</p> Signup and view all the answers

    Study Notes

    Privileges and Roles

    • The revoke statement can be used with restrict to prevent cascading revocation, or with cascade to indicate that revocation should cascade.
    • To avoid confusion when revoking a role, the privilege must be granted only by roles.

    Tuple Relational Calculus

    • A query in the tuple relational calculus is expressed as {t | P(t)}.
    • This query language describes the desired information without giving a specific procedure for obtaining that information.

    Queries

    • The query {t | Э s ε instructor (t[name] = s[name] ∧ Э u ε department (u[dept name] = s[dept name] ∧ u[building] = “Watson”))} finds the names of all instructors whose department is in the Watson building.
    • The symbol ¬ is used in the place of "except".
    • The expression ∀ t ε r (Q(t)) matches the sentence "Find all students who have taken all courses offered in the Biology department."
    • ∀ is used to denote "for all" in SQL.

    Keys

    • A primary key is a constraint that specifies uniqueness.
    • An attribute can be taken as a primary key if it is unique for each tuple.
    • A foreign key is an attribute in a relation that refers to the primary key of another relation.
    • The primary key has to be referred to in another relation to form a foreign key in that relation.

    Relations

    • A referenced relation is the one in which the primary key of one relation is used as a normal attribute in another relation.

    SQL Queries

    • A query must have a from clause to specify the relation from which the values have to be selected.
    • The insert into statement requires the values keyword to insert values into a table.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Test your knowledge on primary keys in databases with this quiz. Learn about the concepts of keys, attributes, and fields. Identify which attribute can be considered as a primary key and which cannot.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser