SELECT grade ,  count(DISTINCT classroom) ,  count(*) FROM list GROUP BY grade
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.
SELECT grade , count ( DISTINCT classroom ) , count ( * ) FROM list GROUP BY grade
select grade , count ( distinct classroom ) , count ( * ) from list group by grade
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 .