统计学生信息表stuinfo中地址address不为空的学生数量,正确的语句是 ( )
A.
select count(*) as 学生数量 from stuinfo
B.
select count(*) as 学生数量 from stuinfo where address is not null
C.
select count(address) as 学生数量 from stuinfo
D.
select count(address) as 学生数量 from stuinfo where address !=null