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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A UNIQUE constraint ensures that a column does not accept NULL values and enforces uniqueness, making it eligible to be referenced by a foreign key from another table. CHECK constraints validate values against a condition, DEFAULT constraints provide default values, and informational constraints are not enforced. Option A is for validation rules, option B provides default values, and option D represents non-enforced constraints.

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