试题详情
- 单项选择题对于主键的说法错误的是()。
A、主键字段输入的数据不允许重复
B、主键字段的数据,允许输入空值
C、若主键由多个键组合而成,则某个主键字段可能存在重复值
D、主键字段可以是字符数据类型
- B
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