判断题学生成绩表中成绩列（Grade）为空可以表示为Grade=NULL。A对B错
判断题
学生成绩表中成绩列（Grade）为空可以表示为Grade=NULL。
A
对
B
错
参考解析
解析：
空值是不能跟任何其他值进行比较的，所以,成绩为空不能表示成Grade=NULL，而必须用IS NULL。
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