题解 | 最差是第几名(二)
最差是第几名(二)
https://www.nowcoder.com/practice/165d88474d434597bcd2af8bf72b24f1
select grade FROM (SELECT grade,SUM(number) OVER(ORDER BY grade) T1, SUM(number) OVER(ORDER BY grade DESC) T2, (SELECT SUM(number) FROM class_grade) T3 FROM class_grade ) T4 WHERE T1>=T3/2 AND T2>=T3/2 ORDER BY grade
求中位数区间：按升序和降序双条件更准确
左累计够一半，右累计够一半，中间区间就是中位数区间
select grade
FROM (SELECT grade,SUM(number) OVER(ORDER BY grade) T1,
SUM(number) OVER(ORDER BY grade DESC) T2,
SUM(number) OVER () T3
FROM class_grade ) T4
WHERE T1>=T3/2 AND T2>=T3/2
ORDER BY grade
