Ways of assigning aliases to a columns

Select Employee_Id As Emp_Id,
Employee_Name As Employee_Name 
From Employee_Master 
Order By Employee_Name

Select Employee_Id Emp_Id,
Employee_Name Employee_Name 
From Employee_Master 
Order By Employee_Name 

Select Employee_Id  = Emp_Id,
Employee_Name = Employee_Name 
From Employee_Master 
Order By Employee_Name