Podcast
Questions and Answers
What SQL keyword is used to change an attribute's definition without renaming it?
What SQL keyword is used to change an attribute's definition without renaming it?
Which statement correctly changes the fax attribute to a new name and data type in the Personnes table?
Which statement correctly changes the fax attribute to a new name and data type in the Personnes table?
What is a potential risk when changing the data type of an attribute?
What is a potential risk when changing the data type of an attribute?
Which SQL command would correctly change the fax column's data type to a larger size without renaming it?
Which SQL command would correctly change the fax column's data type to a larger size without renaming it?
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If you want to use the ALTER TABLE statement to change the definition of fax to num_fax, which aspects must be specified?
If you want to use the ALTER TABLE statement to change the definition of fax to num_fax, which aspects must be specified?
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Study Notes
Changing Attribute Definition
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To change an attribute definition without renaming it, use ALTER TABLE relation MODIFY attribut definition_relative
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Example: ALTER TABLE Personnes MODIFY fax VARCHAR(14)
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To change an attribute definition and rename it, use ALTER TABLE relation CHANGE attribut definition_absolue
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Example: ALTER TABLE Personnes CHANGE fax num_fax VARCHAR(14)
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Caution: If the new data type is incompatible with existing values in the table, those values might be modified or set to zero.
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Description
Explore how to modify attribute definitions in SQL using ALTER TABLE commands. This quiz highlights key distinctions between modifying and renaming attributes, along with crucial cautions regarding data type compatibility. Test your knowledge on the proper usage of SQL syntax for effective database management.
