A.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department RIGHT JOIN Employee WHERE Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
B.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department RIGHT JOIN Employee ON Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
C.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department LEFT JOIN Employee WHERE Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
D.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department LEFT JOIN Employee ON Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID