Podcast
Questions and Answers
Which data types are mentioned as not supporting default values?
Which data types are mentioned as not supporting default values?
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?
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?
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?
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Which of the following statements is true regarding changing default values?
Which of the following statements is true regarding changing default values?
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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:
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ALTER TABLE relation ALTER attribut { SET DEFAULT value | DROP DEFAULT }
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- Example for changing a default value:
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ALTER TABLE Personnes ALTER 'telephone' SET DEFAULT '9999999999'
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- Example for removing a default value:
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ALTER TABLE Personnes ALTER 'telephone' DROP DEFAULT
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- Changes to default values do not affect existing entries that used the previous default value.
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Description
This quiz focuses on changing default attribute values in SQL. It covers the syntax and provides examples for both setting and dropping default values. Test your knowledge on how to handle data types and their implications when altering table properties.
