Which of the following is/are correct?

1999

Which of the following is/are correct?

  1. A.

    An SQL query automatically eliminates duplicates

  2. B.

    An SQL query will not work if there are no indexes on the relations

  3. C.

    SQL permits attribute names to be repeated in the same relation

  4. D.

    None of the above

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Correct answer: D

In standard SQL, duplicate rows are not automatically eliminated; the DISTINCT keyword must be explicitly specified. Queries can function without indexes, and attribute names within a table schema must remain unique. Consequently, the assertions in options A, B, and C are factually incorrect.

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