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【单选题】
下列关于SQL对表的定义的说法中,错误的是:A.
利用create table语句可以定义一个新的数据表结构
B.
利用SQL表的定义语句可以定义表中的主索引
C.
利用SQL表的定义语句可以定义表的域完整性、字段有效性规则等
D.
Alter table可以实现对表数据的修改。
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