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A secondary key is which of the following?

  • A.Nonunique key
  • B.Primary key
  • C.Useful for denormalization decisions
  • D.Determines the tablespace required

Answer: A

Correct answer: Nonunique key

A secondary key identifies a set of rows rather than a single one - all customers in a city, all orders on a date - and is used to speed retrieval on a common search condition. It is a candidate for an index precisely because it is not unique, and it plays no part in identifying rows.

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