175. View the Exhibit and examine the data in the PRODUCTS table.

Which statement would add a column called PRICE, which cannot contain NULL?

A. ALTER TABLE products ADD price NUMBER(8,2) NOT NULL;

B. ALTER TABLE products ADD price NUMBER(8,2) DEFAULT NOT NULL;

C. ALTER TABLE products ADD price NUMBER(8,2) DEFAULT 0 NOT NULL;

D. ALTER TABLE products ADD price NUMBER(8,2) DEFAULT CONSTRAINT p_nn NOT

NULL;

Answer: C

Eg:在test表已经有数据的情况下

1: SQL> alter table test add C number(8,2) default 0 not null;

查询可以发现C列值全为0

2: SQL> alter table test add D number(8,2) not null;

ORA-01758: 要添加必需的 (NOT NULL) 列, 则表必须为空

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