Podcast
Questions and Answers
Which data types are mentioned as not supporting default values?
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?
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?
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?
What SQL command is used to remove a default value from an attribute?
Which of the following statements is true regarding changing default values?
Which of the following statements is true regarding changing default values?
Flashcards
Modifying a Default Value
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
Removing a default value for an attribute. Subsequent records will no longer have a default value for that attribute.
ALTER TABLE ... ALTER ... SET DEFAULT
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
ALTER TABLE ... ALTER ... DROP DEFAULT
Signup and view all the flashcards
Impact of Default Value Changes
Impact of Default Value Changes
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.