根据另一列的最大值获取值

Question

我正在努力想出一个查询来实现SQL中下表所需的返回数据：

我想获得给定日期和期间范围内的最大订单的Value1和Value2。我有以下查询来获取给定范围内每个日期周期对的最大订单编号 - 但是，我似乎无法获得该订单的Value1和Value2。

SELECT 
    Date, Period, MAX(Order)
FROM 
    tableName
WHERE 
    ((Date = '2017-02-27' AND Period>= 10) OR (Date = '2017-02-28' AND Period<= 10))
GROUP BY
    Date, Period

Answer 1

使用row_number()：

SELECT Date, Period, Order
FROM (SELECT t.*,
             ROW_NUMBER() OVER (PARTITION BY Date, Period ORDER BY Order DESC) as seqnum
      FROM tableName 
      WHERE (Date = '2017-02-27' AND Period >= 10) OR
            (Date = '2017-02-28' AND Period <= 10)
     ) t
WHERE seqnum = 1;

Answer 2

您可以使用窗口函数row_number：

select *
from (
    select t.*, row_number() over (
            partition by date, period order by [Order] desc
            ) rn
    from your_table t
    where (
            date = '2017-02-27'
            and Period >= 10
            )
        or (
            date = '2017-02-28'
            and Period <= 10
            )
    ) t
where rn = 1;

Answer 3

如果您想要的只是结果集的顶行，为什么不使用TOP运算符？

SELECT TOP 1 [Date], [Period], [Order], Value1, Value2
FROM tableName
WHERE ((Date = '2017-02-27' AND Period>= 10) OR (Date = '2017-02-28' AND Period<= 10))
ORDER BY [Order] DESC