How does a UNIQUE constraint contribute to maintaining data integrity?
- Allows NULL values in columns, ensuring flexibility
- Ensures that all rows in a table have a unique combination of values in specified columns
- Forces each row in a table to have a different primary key value
- Validates that foreign key values exist in the referenced table
A UNIQUE constraint ensures that all rows in a table have a unique combination of values in the specified columns. This helps maintain data integrity by preventing duplicate records, ensuring that each row is distinct based on the defined uniqueness criteria.
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