问题
单项选择题
Which values are NOT permitted to be part of the primary key
A．alpha-numeric characters
B．punctuation
C．special characters
D．NULL
答案
参考答案：D
搜题请搜索小程序“爱下问搜题”
Which values are NOT permitted to be part of the primary key
A．alpha-numeric characters
B．punctuation
C．special characters
D．NULL
参考答案：D