1三種排序（開窗）第幾名/前幾名/topN

求每個學生成績第二高的科目-排序

思路

t2表：對每個學生 的所有課程 的成績排序，定好新列rn；（dense_rank() over (),）（partition by student order by socre）（開窗函數:基于每個student 對 score排序）

    select class,student,score,dense_rank() over (partition by student order by score DESC) as rnfrom day_sql.day2_kaichaunghanshu

t3表：取a1表中rn=2的數據。

select class,student,score
from (select class,student,score,dense_rank() over (partition by student order by score) as rnfrom day_sql.day2_kaichaunghanshu)t2 where rn=2;

4種排序開窗函數

3種序號排序
rank() -12245
dense_rank() -12234
row_number() -12345
1種百分比排序
percent_rank() - 百分比超過了多少人