如何获得多列之间的2个最大值？

Question

我想弄清楚如何从5个字段获得2个最高值.我知道这个greatest功能,但我也不知道如何取出第二个最高值.

基本上,该表有5个NUMBER类型字段.在此示例中,最后两列是我想要的结果.

| Score1 | Score2 | Score3 | Score4 | Score5 | | Highest1_value | Highest2_value 
+--------+--------+--------+--------+--------+ +----------------+---------------
|    10  |    20  |    30  |    40  |   50   | |       50       |       40
|    20  |    20  |    12  |    17  |    0   | |       20       |       20
|     7  |     7  |     7  |     7  |   11.1 | |       11.1     |        7
|    10  |    10  |    10  |    10  |   10   | |       10       |       10

Answer 1

对数据进行逆透视并用于row_number获取每个 id 的前 2 个最高分数。

select id
,max(case when rnum=1 then val end) as highest_1
,max(case when rnum=2 then val end) as highest_2
from (select id,score,val,row_number() over(partition by id order by val desc) as rnum
      from (select * from t --replace this with your tablename
            unpivot (val for score in (score1,score2,score3,score4,score5)) p
          ) tbl
      ) tbl
group by id