Oracle.1Z0-051.175q(17)

OCP 11g 051题库

A. A foreign key cannot contain NULL values.

B. A column with the UNIQUE constraint can contain NULL values.

C. A constraint is enforced only for the INSERT operation on a table.

D. A constraint can be disabled even if the constraint column contains data.

E. All constraints can be defined at the column level as well as the table level.

Answer: BD

QUESTION 29

Which two statements are true regarding constraints? (Choose two.)

A. A foreign key cannot contain NULL values.

B. The column with a UNIQUE constraint can store NULLS .

C. A constraint is enforced only for an INSERT operation on a table.

D. You can have more than one column in a table as part of a primary key.

Answer: BD

QUESTION 30

Evaluate the following CREATE TABLE commands:

CREATE TABLE orders

(ord_no NUMBER(2) CONSTRAINT ord_pk PRIMARY KEY,

ord_date DATE,

cust_id NUMBER(4));

CREATE TABLE ord_items

(ord_no NUMBER(2),

item_no NUMBER(3),

qty NUMBER(3) CHECK (qty BETWEEN 100 AND 200),

expiry_date date CHECK (expiry_date > SYSDATE), CONSTRAINT it_pk PRIMARY KEY (ord_no,item_no),

CONSTRAINT ord_fk FOREIGN KEY(ord_no) REFERENCES orders(ord_no));

The above command fails when executed. What could be the reason?

A. SYSDATE cannot be used with the CHECK constraint.

B. The BETWEEN clause cannot be used for the CHECK constraint.

C. The CHECK constraint cannot be placed on columns having the DATE data type.

D. ORD_NO and ITEM_NO cannot be used as a composite primary key because ORD_NO is also the FOREIGN KEY.

Answer: A

QUESTION 31

Evaluate the following SQL commands:

SQL>CREATE SEQUENCE ord_seq

INCREMENT BY 10

START WITH 120

MAXVALUE 9999

搜索“diyifanwen.net”或“第一范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，第一范文网，提供最新小学教育Oracle.1Z0-051.175q(17)全文阅读和word下载服务。