question: Find the student ID and login name of the student with the most course enrollments
#1 return students 
#2 return course enrollments of  #1 
#3 return number of #2 
#4 return #1 where  #3 is  highest 
#5 return student ID of  #4 
#6 return login name of  #4 
#7 return #5 ,   #6