问题
单项选择题
从学生选课信息表中找出无成绩的元组的SQL语句是( )。
A.SELECT*FROM sc WHERE grade=NULL
B.SELECT*FROM sc WHERE grade IS"
C.SELECT*FROM sc WHERE grade IS NULL
D.SELECT*FROM sc WHERE grade="
答案
参考答案:C
从学生选课信息表中找出无成绩的元组的SQL语句是( )。
A.SELECT*FROM sc WHERE grade=NULL
B.SELECT*FROM sc WHERE grade IS"
C.SELECT*FROM sc WHERE grade IS NULL
D.SELECT*FROM sc WHERE grade="
参考答案:C