ocp試題解析：11g-1Z0-051-v9.02-030題，完整題庫(kù)請(qǐng)點(diǎn)擊這里聯(lián)系老師咨詢了解

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), 系統(tǒng)時(shí)間是變化的，不能作為約束

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

試題解析：

A答案：sysdate不能用在check約束中，A正確

B答案：BETWEEN 可以用在check約束中，B錯(cuò)誤

C答案：check約束可以作用在data類型的列上，C錯(cuò)誤。

D答案：外鍵約束和字段可以和本表組合成主鍵