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Which of the following are integrity controls that a DBMS may support?

  • A.Assume a default value in a field unless a user enters a value for that field.
  • B.Limit the set of permissible values that a field may assume.
  • C.Limit the use of null values in some fields.
  • D.All of the above.

Answer: D

Correct answer: All of the above.

All three are integrity controls the DBMS itself can enforce: a default supplied when no value is given, a domain constraint limiting the permissible values, and a not-null constraint requiring one. Placing them in the database rather than in each application means every route to the data is checked identically.

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