message: Update compute-the-rank-as-a-percentage.sql
diff: SELECT student_id,
  department_id,
  ROUND(100 * PERCENT_RANK() OVER (PARTITION BY department_id
  - ORDER BY mark DESC) , 2) AS percentage
  + ORDER BY mark DESC)
  + , 2) AS percentage
  +FROM Students;
  +
  +
  +# Time: O(nlogn)
  +# Space: O(n)
  +SELECT student_id,
  + department_id,
  + ROUND(IFNULL(100 * (RANK() OVER (PARTITION BY department_id ORDER BY mark DESC) - 1) /
  + (COUNT(1) OVER (PARTITION BY department_id) - 1)
  + , 0)
  + , 2) AS percentage
  FROM Students;
  