Question

如何从多列中选择最低的3个数字？

id          num1        num2        num3        num4        num5
----------- ----------- ----------- ----------- ----------- -----------
1           1           6           5           1           2
2           6           2           2           3           2
3           2           1           2           1           5
4           4           1           1           5           7
5           5           1           4           7           8

例如

（来自id 1的最低2个值）＆gt; （（来自id 5的最低2个值）

Answer 1

一种方法使用cross apply：

select t.id, v.num
from t cross apply
     (select top 3 num
      from (values (num1), (num2), (num3), (num4), (num5)) v(num)
      order by num asc
     ) v;

如果你想让它们在同一行，那么重新转动：

select t.id, v.*
from t cross apply
     (select max(case when seqnum = 1 then num end) as num1,
             max(case when seqnum = 2 then num end) as num2,
             max(case when seqnum = 3 then num end) as num3                 
      from (select num, row_number() over (order by num) as seqnum
            from (values (num1), (num2), (num3), (num4), (num5)) v(num)
           ) v
      ) v;

Answer 2

执行order by desc并选择top行，例如

select top 3 num1, num2, num3
from tbl1
order by num1 desc, num2 desc, num3 desc

从多个列中查找最低值？

2 个答案: