计算机二级
下列语句错误的是( )A.select * from orders where ordername is not null;B.select * from orders where ordernameC.select * from orders where ordername is null;D.select * from orders where ordername not is null;
题目
下列语句错误的是( )
A.select * from orders where ordername is not null;
B.select * from orders where ordername<>null;
C.select * from orders where ordername is null;
D.select * from orders where ordername not is null;
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