获取每个 ID 的最新记录 [英] get latest record for each ID

问题描述

我想获取每台服务器的最新记录.

I would like to get the latest record for each server.

以下是一些示例数据:

TimeGenerated        SourceName            ComputerName  Message
2014-11-22 21:48:30  Windows Update Agent  Server1       Update Failed
2014-11-22 21:42:30  Windows Update Agent  Server2       Update Failed
2014-11-22 21:45:30  Windows Update Agent  Server2       Update Failed
2014-11-22 21:43:30  Windows Update Agent  Server1       Update Failed

期望的输出:

TimeGenerated        SourceName            ComputerName  Message
2014-11-22 21:48:30  Windows Update Agent  Server1       Update Failed
2014-11-22 21:45:30  Windows Update Agent  Server2       Update Failed

我试过了:

SELECT * FROM TABLE 
GROUP BY ComputerName 
ORDER BY TimeGenerated ASC 

但这会输出不一致的结果，并且在大多数情况下不会给我最新的结果.

But that outputs inconsistent results and does not give me the latest in most cases.

我也尝试了一些子查询，但都失败了.

I also tried some sub queries, but failed miserably.

推荐答案

SELECT *
FROM yourtable
INNER JOIN (
   SELECT MAX(timeGenerated) as maxtime, ComputerName
   FROM yourtable
   GROUP BY ComputerName
) AS latest_record ON (yourtable.timeGenerated = maxtime)
   AND (latest_record.ComputerName = yourtable.ComputerName)

内部查询获取每个计算机名称的最新时间戳.然后，外部查询根据内部查询找到的时间/计算机名称，结合该查询结果从表中获取其余字段.如果您以相同的最大次数记录了两个事件，您将获得该计算机名的两条记录.

Inner query gets the latest timestamp for every computer name. The outer query then joins against that query result to fetch the rest of the fields from the table, based on the time/computername the inner query finds. If you have two events logged with identical max times, you'd get two records for that computername.

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