Multiple choice technology databases

Which of the following is used to indicate a column will not accept NULL values and can be referenced in another table's foreign key specification?

  1. Check constraint

  2. Default constraint

  3. Unique constraint

  4. Informational constraint
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C Correct answer
Explanation

A unique constraint ensures all values in a column are different and cannot be NULL. This makes it suitable for foreign key references since other tables need reliable, non-null values to establish relationships.

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