无法在 SQL Server 中执行 Group-by答案

【问题标题】：Not able to perform Group-by in SQL Server无法在 SQL Server 中执行 Group-by
【发布时间】：2019-12-06 04:58:46
【问题描述】：

试图过滤细节

需要最大BookingVersion group by shipmentNumber, shipmentDate, 的唯一行

select max(BookingVersion) BookingVersion, flightId, shipmentNumber, shipmentDate, FlightOffPoint, IIF(BookingStatusCode = 'XX', 'XX','SS') BookingStatusCode
from Exp_BookingDelta where flightid='625436' 
group by flightId, shipmentNumber, shipmentDate, FlightOffPoint, BookingStatusCode  
order by max(BookingVersion) desc

谁能解释一下，我错过了什么？

目前的结果：

BookingVersion  flightId    shipmentNumber  shipmentDate    FlightOffPoint  BookingStatusCode
4               625436      61823647238     2019-12-04      LHR             XX
2               625436      61823647238     2019-12-04      LHR             SS
1               625436      61826374895     2019-12-06      LHR             XX
0               625436      61825364780     2019-11-26      LHR             SS
0               625436      61825364791     2019-11-26      LHR             SS
0               625436      61825364802     2019-11-26      LHR             SS
0               625436      61826374895     2019-12-06      LHR             SS

预期结果：

BookingVersion  flightId    shipmentNumber  shipmentDate    FlightOffPoint  BookingStatusCode
4               625436      61823647238     2019-12-04      LHR             XX
1               625436      61826374895     2019-12-06      LHR             XX
0               625436      61825364780     2019-11-26      LHR             SS
0               625436      61825364791     2019-11-26      LHR             SS
0               625436      61825364802     2019-11-26      LHR             SS

【问题讨论】：

问题是什么？请添加您的查询和您得到的错误。
请提出您的问题，到目前为止您已经尝试过什么
@juergend 添加了查询。
@MukeshArora 已添加。
您能否解释一下您的逻辑是如何返回“预期”行？

标签： sql sql-server join group-by sql-order-by

【解决方案1】：

请尝试：

select 
   max(BookingVersion) BookingVersion, flightId, shipmentNumber, shipmentDate, FlightOffPoint, MAX(BookingStatusCode) BookingStatusCode
from
   Exp_BookingDelta where flightid='625436' 
group by flightId, shipmentNumber, shipmentDate, FlightOffPoint
order by max(BookingVersion) desc

或

select 
    max(BookingVersion) BookingVersion, flightId, shipmentNumber, shipmentDate,
    IIF((select count(*) from Exp_BookingDelta b where b.FlightId=a.FlightId and b.ShimpmentNumber=a.ShimpmentNumber)>0, 'XX', 'SS') BookingStatusCode
from 
    Exp_BookingDelta where flightid='625436' 
group by flightId, shipmentNumber, shipmentDate, FlightOffPoint  
order by max(BookingVersion) desc

【讨论】：

【解决方案2】：

我建议使用窗口函数来查找您想要的特定记录。喜欢：

;with c as (select BookingVersion, flightId, shipmentNumber, shipmentDate, FlightOffPoint, IIF(BookingStatusCode = 'XX', 'XX','SS') BookingStatusCode
                 , row_number() over (partition by shipmentNumber order by BookingVersion desc) rn
              from Exp_BookingDelta
             where flightid='625436')
select BookingVersion, flightId, shipmentNumber, shipmentDate, FlightOffPoint, BookingStatusCode
  from c
 where rn = 1

【讨论】：

【解决方案3】：

请根据我准备的预期输出检查此查询。

注意：请根据您的实际查询更改此查询。

查询

DECLARE @Table TABLE
(
    BookingVersion INT,
    flightId INT,
    shipmentNumber VARCHAR(20),
    shipmentDate DATE,
    FlightOffPoint VARCHAR(10),
    BookingStatusCode VARCHAR(10)
)

INSERT INTO @Table 
VALUES(
4 ,              625436 ,     '61823647238',    '2019-12-04',  'LHR','XX'),
(2,               625436,     ' 61823647238',    '2019-12-04',  'LHR','SS'),
(1,               625436,     ' 61826374895',    '2019-12-06',  'LHR','XX'),
(0,               625436,     ' 61825364780',    '2019-11-26',  'LHR','SS'),
(0,               625436,     ' 61825364791',    '2019-11-26',  'LHR','SS'),
(0,               625436,     ' 61825364802',    '2019-11-26',  'LHR','SS'),
(0,               625436,     ' 61826374895',    '2019-12-06',  'LHR','SS')


SELECT MAX(BookingVersion) AS BookingVersion,
    flightId,
    shipmentNumber,
    shipmentDate,
    FlightOffPoint, 
    MAX(BookingStatusCode) AS BookingStatusCode
FROM @Table 
GROUP BY flightId, shipmentNumber, shipmentDate, FlightOffPoint
ORDER BY MAX(BookingVersion) DESC

输出

【讨论】：