052-224(新增70题2018)

View the Exhibit to see the data in the emp table.

You created a PRIMARY KEY constraint on the empno column of the emp table, and the constraint is not deferred.

Which two statements are true in this scenario? (Choose two.)

Exhibit:

A. No index would be created or used in this case.

B. A unique index on the empno column would be created.

C. A CHECK constraint would be enforced on the empno column.

D. A NOT NULL constraint would be enforced on the empno column.

E. A bitmap unique index would be created on the empno column.

Answer: BD

Primary Key Constraints

The Oracle Database implementation of the primary key constraint guarantees that the following statements are true:

• No two rows have duplicate values in the specified column or set of columns.

• The primary key columns do not allow nulls.

转载于:https://www.cnblogs.com/Babylon/p/8615990.html