1Z0-051 30. Evaluate thefollowing CREATE TABLE commands

30. Evaluate thefollowing CREATE TABLE commands:

CREATE TABLEorders

(ord_noNUMBER(2) CONSTRAINT ord_pk PRIMARY KEY,

ord_date DATE,

cust_idNUMBER(4));

CREATE TABLEord_items

(ord_noNUMBER(2),

item_noNUMBER(3),

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

expiry_date dateCHECK (expiry_date > SYSDATE),

CONSTRAINT it_pkPRIMARY KEY (ord_no,item_no),

CONSTRAINTord_fk FOREIGN KEY(ord_no) REFERENCES orders(ord_no));

The abovecommand fails when executed. What could be the reason?

A. SYSDATEcannot be used with the CHECK constraint.

B. The BETWEENclause cannot be used for the CHECK constraint.

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

D. ORD_NO andITEM_NO cannot be used as a composite primary key because ORD_NO is also the

FOREIGN KEY.

答案：A。sysdate是变量所以不能用在check约束中，但是可以用作默认值