單項(xiàng)選擇題

在Oracle中,有一個教師表teacher的結(jié)構(gòu)如下:
IDNUMBER(5),NAMEVARCHAR2(25),EMAILVARCHAR2(50)
下面哪個語句顯示沒有Email地址的教師姓名()

A.select name from teacher where email=null;
B.select name from teacher where email〈〉null;
C.select name from teacher where email is null;
D.select name from teacher where email is not null;

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