For each grade, return the grade number, the number of classrooms used for the grade, and the total number of students enrolled in the grade.
return grades ;return grade    number   of  #1 ;return classrooms used for #1 ;return number of #3 for each #1 ;return students enrolled in #1 ;return number   of  #5 for each #1 ;return #2 ,   #4 , #6
['select', 'aggregate', 'project', 'group', 'project', 'group', 'union']