Multiple choice technology

Which statements are true regarding views?

  1. A subquery that defines a view cannot include the GROUP BY clause.

  2. A view that is created with the subquery having the DISTINCT keyword can be updated.

  3. .A view that is created with the subquery having the pseudo column ROWNUM keyword cannot be

  4. A data manipulation language (DML) operation can be performed on a view that is created with the
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C,D Correct answer
Explanation

Views have specific restrictions on updability. A view defining subquery CAN include GROUP BY clause - this is allowed. Views created with DISTINCT keyword are NOT updatable because the DISTINCT makes row identification ambiguous. Views with ROWNUM pseudo-column are NOT updatable because ROWNUM values are not stable. DML operations CAN be performed on simple views that meet updability criteria (no joins, aggregates, DISTINCT, etc.).

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