Question

我有一个固有的SQL连接表来给我所需的结果，但返回的数据集（C＃）不同，因为它现在重命名列名或以1递增。

SELECT TOP 1 *
FROM [dbo].[ComputerState] as a
INNER JOIN [dbo].[ComputerState] as b ON a.ServiceName != b.ServiceName
WHERE a.State = 5 and b.State = 5
AND a.ServiceName IN (
 SELECT [ServiceName] FROM [dbo].[ComputerState]
)

问题是它返回像这样的行，

[ComputerName, ServiceName, ComputerName1, ServiceName1]
[server, service, server2, service2]

我可以像原始表格格式一样返回

[ComputerName, ServiceName]
[server, service]
[Server2, service2]

我当然可以从列名中删除INT 1，但如果我可以避免这种情况会很好。

Answer 1

您可以选择a.*代替*。此外，您可能希望使用WITH TIES

的TOP选项

SELECT TOP 1 WITH TIES a.*
FROM [dbo].[ComputerState] as a
INNER JOIN [dbo].[ComputerState] as b ON a.ServiceName != b.ServiceName
WHERE a.State = 5 and b.State = 5
AND a.ServiceName IN (
 SELECT [ServiceName] FROM [dbo].[ComputerState] 
)

但是，使用TOP而不使用ORDER BY通常是一个坏主意。我不知道你打算查询什么（访问同一桌子三次通常是一个坏主意）。

Answer 2

在输出中使用UNION，您可以将结果移到彼此之下：

SELECT TOP 1 a.*
FROM [dbo].[ComputerState] as a
INNER JOIN [dbo].[ComputerState] as b ON a.ServiceName != b.ServiceName
WHERE a.State = 5 and b.State = 5
AND a.ServiceName IN (
 SELECT [ServiceName] FROM [dbo].[ComputerState]
)

UNION ALL

SELECT TOP 1 b.*
FROM [dbo].[ComputerState] as a
INNER JOIN [dbo].[ComputerState] as b ON a.ServiceName != b.ServiceName
WHERE a.State = 5 and b.State = 5
AND a.ServiceName IN (
 SELECT [ServiceName] FROM [dbo].[ComputerState]
)

P.S。说实话，这可能会导致性能提升，因为INNER JOIN将会完成两次。他们可能是一个更有效的问题，但我不确定如何做得最好。

在INNER JOIN

2 个答案: