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Which of the following is true of an index used to support a

题目
单选题
Which of the following is true of an index used to support a UNIQUE constraint?（）
A

It must have the UNIQUE attribute.

B

It cannot be created explicitly by the user.

C

It must have the UNIQUE and CLUSTER attributes.

D

It must have the UNIQUE WHERE NOT NULL attribute.

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相似问题和答案

第1题：

According to Paragraph 2, which of the following is true of colours?

A Colors are encoded in girls' DNA

B Blue used to be regarded as the color for girls

C Pink used to be a neutral color in symbolizing genders

D White is preferred by babies


正确答案：B

第2题：

Which of the following is true of an index used to support a UNIQUE constraint?()

A.It must have the UNIQUE attribute.

B.It cannot be created explicitly by the user.

C.It must have the UNIQUE and CLUSTER attributes.

D.It must have the UNIQUE WHERE NOT NULL attribute.


参考答案：A

第3题：

Consider the following:Which statement best describes the meaning of the value for the key_len column?()

A.It shows the total size of the index row

B.It shows how many columns in the index are examined

C.It shows the number of characters indexed in the key

D.It shows how many bytes will be used from each index row


参考答案：D

第4题：

Which of the following are true of both OSPFv2 and OSPFv3?（）

  • A、The method of choosing an OSPF router ID
  • B、Verification checks that must be validated before two routers can become OSPF neighbors
  • C、Support for route tags
  • D、Support for multiple instances per inter face

正确答案:A,C

第5题：

The following configuration command was entered into a router:ip route 172.16.3.0 255.255.255.0 192.168.2.4 Which of the following statements are true regarding this configuration change?()

A. The default administrative distance is used.

B. The command is used to establish a static route.

C. The command is used to configure the router interfaces.

D. The command is used to establish a stub network.

E. The subnet mask for the source address is 255.255.255.0


参考答案：A, B

第6题：

Which of the following wireless standards was the FIRST standard to be ratified and is used to support legacy wireless devices?()

A.802.11a

B.802.11g

C.802.11b

D.802.11n


参考答案：C

第7题：

The man page for command shows the following syntax: The man page for command shows the following syntax: command [ －a | －b ] Which of the following statements is true regarding this entry?()

A. Either the -a or flag -b may be used, but not both.

B. If the flag -a is used then the flag -b also must be used.

C. One of the -a or -b flags must be used, but not both at the same time.

D. Both the flags may be used together, but neither are mandatory.


参考答案：D

第8题：

The InnoDB engine has a feature known as clustered indexes.Which three statements are true about clustered indexes as used in InnoDB?()

A.A primary key must exist for creation of a clustered index

B.A clustered index allows fulltext searching within InnoDB

C.The first unique index is always used as a clustered index and not a primary key

D.A clustered index provides direct access to a page containing row data

E.If no indexes exist, a hidden clustered index is generated based on row IDs

F.A primary key is used as a clustered index

G.A clustered index is a grouping of indexes from different tables into a global index for faster searching


参考答案：D, E, F

第9题：

Which of the following is true of the squirrel bridge?__________

A.It was replaced by a longer one
B.It was built from wood and metal
C.it was rebuilt after years of use
D.It was designed by Bill Hutch

答案：C
解析：
根据文章倒数第二段中的“In 1983，after 20 years of use，Peters took down the wom．outbridge．Repairs were made and crosspieces were replaced．"可知，绳索用了20年后，Peters进行了修缮，并替换上了新的绳索。因此C为正确答案。文中没有涉及是否替换的绳索更长：第五段中提到绳索是铝制的；Bill Hutch是参与施工者，而非设计者，故均排除。

第10题：

Examine the following output： SQL> SELECT index_name，status FROM dba_indexes WHERE status=’UNUSABLE’； INDEX_NAME STATUS------------------------------ ----------- EIND UNUSABLE Which two statements about the above index are true（）

  • A、It is ignored by the query optimizer.
  • B、It is not used while the index is being rebuilt.
  • C、The index cannot be rebuilt， and has to be re-created.
  • D、The index is automatically rebuilt when used the next time

正确答案:A,B

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