查找每行列值的中位数

Question

我试过下面的查询，但显示的中值是错误的。

询问

select 
(select cast(Avg(TotAvg * 1.0 )as decimal(6,2))
 from (values (convert(decimal(6,2), a)),(convert(decimal(6,2), b))
             ,(convert(decimal(6,2), c)),(convert(decimal(6,2), d))
             ,(convert(decimal(6,2), e)),(convert(decimal(6,2), f))
             ,(convert(decimal(6,2), g)),(convert(decimal(6,2), h))
             ,(convert(decimal(6,2), i)),(convert(decimal(6,2), j))
             ,(convert(decimal(6,2), k)),(convert(decimal(6,2), l))
             ,(convert(decimal(6,2), m)),(convert(decimal(6,2), n))
             ,(convert(decimal(6,2), o)),(convert(decimal(6,2), p))
             ,(convert(decimal(6,2), q)),(convert(decimal(6,2), r))
             ,(convert(decimal(6,2), s)),(convert(decimal(6,2), t))
             ,(convert(decimal(6,2), u))
    ) as Totalavg(TotAvg)
) as Median
from temp

列值是一行中的 a 到 u。

表值

First row - 1,5,6,7,8,2,6,3,4,5,2,1,6,5,7,8,2,7,6,2,8
Second row - 1,5,6,7,8,2,2,3,2,4,2,1,4,5,9,8,2,7,6,2,8

创建表脚本

create table temp 
(
    id int identity(1,1),
    a decimal(6,2),
    b decimal(6,2),
    c decimal(6,2),
    d decimal(6,2),
    e decimal(6,2),
    f decimal(6,2),
    g decimal(6,2),
    h decimal(6,2),
    i decimal(6,2),
    j decimal(6,2),
    k decimal(6,2),
    l decimal(6,2),
    m decimal(6,2),
    n decimal(6,2),
    o decimal(6,2),
    p decimal(6,2),
    q decimal(6,2),
    r decimal(6,2),
    s decimal(6,2),
    t decimal(6,2),
    u decimal(6,2)
)

插入表脚本

insert into temp
    (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u)
values
    (1,5,6,7,8,2,6,3,4,5,2,1,6,5,7,8,2,7,6,2,8)

insert into temp
    (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u)
values
    (1,5,6,7,8,2,2,3,2,4,2,1,4,5,9,8,2,7,6,2,8)

Answer 1

第一步是将列反透视为行。然后您可以使用 row_number 枚举值并从那里选择中间值：

select id, avg(val)
from ( 
    select id, val
         , count(*) over (partition by id) as c
         , row_number() over (partition by id order by val) as rn
    from temp unpivot (
             val for col in (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u)
         ) as x 
) as y
where rn IN ((c + 1)/2, (c + 2)/2) 
group by id;