从Employee表中统计出所有生日(Birthday)信息的员工人数
A.
SELECT COUNT(Birthday) AS 有出生记录的员工数 FROM Employee
B.
SELECT COUNT(*) AS 有出生记录的员工数 FROM Employee where Birthday is not null
C.
SELECT COUNT(*) AS 有出生记录的员工数 FROM Employee
D.
SELECT COUNT(*) 有出生记录的员工数 ,name 员工姓名 FROM Employee