使用 OVER 的第二个最大值

Question

我正在尝试将一个需求源与前两个不同的最高需求源进行比较，以便我可以在 SQL 中执行一些操作。

这是我所拥有的最大值和特定需求，但我不知道如何找到第二个最大值。我见过max(x) where x <> max(x)，但我不确定如何将其用于 Windows 功能。

选择 row_id_str、Max_NR、Max_R

from(
    select row_id_str,
        MAX(NR_close) OVER (PARTITION BY row_id_str) as Max_NR,
        MAX(R_close) OVER (PARTITION BY row_id_str) as Max_R
    from(
        SELECT  row_id_str, demand, close,
        sum(if(demand = 'root', close, 0)) as R_close,
        sum(if(demand != 'root', close, 0)) as NR_close
        FROM [scratch] group by 1,2,3
        order by row_id_str, close desc)
    group by row_id_str, NR_close, R_close)
group by 1,2,3

解决方案

select row_id_str, Max_NR, Max_R, Sum(if(RN=2, NR_close, 0)) as Second_Max
from(
    select row_id_str,  NR_close,
    MAX(NR_close) OVER (PARTITION BY row_id_str) as Max_NR,
    MAX(R_close) OVER (PARTITION BY row_id_str) as Max_R,
    ROW_NUMBER() over (partition by row_id_str order by NR_close desc) as RN
    from(
        SELECT  row_id_str, demand_rtb_name, close, sum(if(demand_rtb_name = 'rubicon', close, 0)) as R_close, sum(if(demand_rtb_name != 'rubicon', close, 0)) as NR_close
        FROM [scratch.oRubicon1_3] group by 1,2,3
        order by row_id_str, close desc)
    group by row_id_str, close, NR_close, R_close)
group by 1,2,3,

Answer 1

您可以将MAX 与ROW_NUMBER() 结合使用。

围绕它包装一个新的选择，并选择带有WHERE RowNumber = 2的特定行

SELECT 
    tMax.row_id_str,
    tMax.MyMax,
    ROW_NUMBER() OVER (ORDER BY(tMax.MyMax)) AS RowNumber
FROM
    (SELECT 
        t.row_id_str, 
        MAX(t.NR_close)
    FROM
        table AS t
    GROUP BY
        t.row_id_str
    ) AS tMax