Which constraint prevents duplicate values in a database column?

Options

  • A. DEFAULT Constraint
  • B. UNIQUE Constraint
  • C. CHECK Constraint
  • D. More than one of the above
  • E. None of the above

Correct Answer (Detailed Explanation is Below)

B. UNIQUE Constraint

Detailed Explanation

Explanation: The UNIQUE constraint ensures that duplicate values are not allowed in a column or combination of columns. NULL handling may vary by DBMS.