多項選擇題

Which statements are correct regarding indexes？（）

A. When a table is dropped， the corresponding indexes are automatically dropped.
B. For each DML operation performed， the corresponding indexes are automatically updated.
C. Indexes should be created on columns that are frequently referenced as part of an expression.
D. A non-deferrable PRIMARY KEY or UNIQUE KEY constraint in a table automatically creates a uniqueindex.

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單項選擇題

Evaluate the following SQL statements that are issued in the given order：

What would be the status of the foreign key EMP_MGR_FK？（）

A. It would be automatically enabled and deferred.
B. It would be automatically enabled and immediate.
C. It would remain disabled and has to be enabled manually using the ALTER TABLE command.
D. It would remain disabled and can be enabled only by dropping the foreign key constraint and re-creating it.

單項選擇題

Which statement is true regarding Flashback Version Query？（）

A. It returns versions of rows only within a transaction.
B. It can be used in subqueries contained only in a SELECT statement.
C. It will return an error if the undo retention time is less than the lower bound time or SCN specified.
D. It retrieves all versions including the deleted as well as subsequently reinserted versions of the rows.

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Which statements are correct regarding indexes？ （）

你可能感興趣的試題

Evaluate the following SQL statements that are issued in the given order： What would be the status of the foreign key EMP_MGR_FK？（）

Which statement is true regarding Flashback Version Query？（）

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Which statements are correct regarding indexes？（）

Evaluate the following SQL statements that are issued in the given order：

What would be the status of the foreign key EMP_MGR_FK？（）

Which statement is true regarding Flashback Version Query？（）