SQL 如何 return 具有最近日期和最高 int 值的记录

Question

我必须 return SQL 数据库中的最新行，按 CallID 分组。本例中的 'most recent' 表示最近的 DepartureDate 和该日期的最高 Departuretime (int)。请参阅以下示例供您参考：

set dateformat dmy
create table #Temp
(
Callid nvarchar(6), 
Linenum nVarchar(6), 
Engineerid nvarchar (4), 
Departuredate DateTime, 
Departuretime int
)
insert into #Temp 
Values (
'100000','1','AToo','05/09/2017','57896'),
('100000','1.5','DBok','05/09/2017','57898'),
('100000','1.75','DBok','05/09/2017','57895'),
('100000','2','GKar','04/09/2017','59805'),
('100000','3','ALee','05/09/2017','54895'),
('100001','1','GKar','08/09/2017','54000'),
('100001','2','GKar','08/09/2017','58895'),
('100001','2.25','ALee','08/09/2017','56875'),
('100001','2.5','DBok','07/09/2017','59000')

select * from #Temp
drop table #Temp

上面我要return的，就是下面两条记录：

CallID  Linenum  Engineerid  Departuredate  Departuretime
100000  1.5      DBok        05/09/2017     57898
100001  2        GKar        08/09/2017     58895

Answer 1

您可以使用 row_number window 函数按 callid 对记录进行排序，然后只取第一个：

SELECT CallID, Linenum, Engineerid, Departuredate, Departuretime
FROM   (SELECT CallID, Linenum, Engineerid, Departuredate, Departuretime,
               ROW_NUMBER() OVER (PARTITION BY CallID
                                  ORDER BY Departuredate DESC, Departuretime DESC) AS rn
        FROM   #Temp) t
WHERE  rn = 1

Answer 2

你可以使用 TOP 1 WITH TIES

的技巧

select TOP 1 WITH TIES * 
from #Temp
ORDER BY ROW_NUMBER() OVER (PARTITION BY CallId ORDER BY Departuredate DESC,Departuretime DESC);

ORDER BY ROW_NUMBER() OVER(PARTITION BY CallId...) 将为每个 CallId 重新开始行编号。所以有很多行带有 1 标记最高。 TOP 1 将只选择结果集的第一行，但是对于 WITH TIES 它将 return 所有 first 行，如果有多个.

SQL 如何 return 具有最近日期和最高 int 值的记录

SQL How to return the record with the most recent date and also highest int value

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tsql

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