SQL Default Attribute Values

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson
Download our mobile app to listen on the go
Get App

Questions and Answers

Which data types are mentioned as not supporting default values?

  • VARCHAR
  • BLOB (correct)
  • TEXT (correct)
  • INTEGER

What is the correct SQL syntax to change the default value of an attribute?

  • CHANGE TABLE relation DEFAULT value
  • ALTER TABLE relation ALTER attribut SET DEFAULT value (correct)
  • ALTER relation DROP DEFAULT
  • ALTER relation SET DEFAULT value

What happens to existing records when the default value for an attribute is changed?

  • The database will throw an error.
  • Existing records retain the old default value. (correct)
  • All existing records will update to the new default value.
  • Existing records are deleted.

What SQL command is used to remove a default value from an attribute?

<p>ALTER TABLE relation ALTER attribut DROP DEFAULT (D)</p> Signup and view all the answers

Which of the following statements is true regarding changing default values?

<p>New records will use the updated default value after changes. (C)</p> Signup and view all the answers

Flashcards

Modifying a Default Value

Changing the default value of an attribute in a database, setting it to a new value. This affects only new records, not existing ones.

Removing a Default Value

Removing a default value for an attribute. Subsequent records will no longer have a default value for that attribute.

ALTER TABLE ... ALTER ... SET DEFAULT

An SQL command used to alter the default value of an attribute in a table.

ALTER TABLE ... ALTER ... DROP DEFAULT

An SQL command used to remove the default value of an attribute from a table.

Signup and view all the flashcards

Impact of Default Value Changes

Changing a default value in a database does not retroactively change values in existing rows. Only new rows added after the change will use the new (or removed) default value.

Signup and view all the flashcards

Study Notes

Changing Default Attribute Values

  • Changing or removing default attribute values is possible.
  • Be mindful of data types like BLOB and TEXT, which may not accept default values.
  • Syntax for changing default values:
    • ALTER TABLE relation ALTER attribut { SET DEFAULT value | DROP DEFAULT }
  • Example for changing a default value:
    • ALTER TABLE Personnes ALTER 'telephone' SET DEFAULT '9999999999'
  • Example for removing a default value:
    • ALTER TABLE Personnes ALTER 'telephone' DROP DEFAULT
  • Changes to default values do not affect existing entries that used the previous default value.

Studying That Suits You

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

Quiz Team

More Like This

SQL Basics Quiz
10 questions

SQL Basics Quiz

HaleRetinalite2094 avatar
HaleRetinalite2094
ClassicModels SQL Exercises
26 questions
Use Quizgecko on...
Browser
Browser