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Mysql 按设备ID查询最后一个条目组_Mysql_Database_Distinct - Fatal编程技术网

Mysql 按设备ID查询最后一个条目组

Mysql 按设备ID查询最后一个条目组,mysql,database,distinct,Mysql,Database,Distinct,我的数据库表日志如下所示: SELECT * FROM ( SELECT deviceid, MAX(poll_date) AS md FROM logs GROUP BY deviceid ) q JOIN logs l ON l.deviceid = q.deviceid AND l.poll_date = q.md 我想提取设备的最后一个条目,

我的数据库表日志如下所示:

SELECT  *
FROM    (
        SELECT  deviceid, MAX(poll_date) AS md
        FROM    logs
        GROUP BY
                deviceid
        ) q
JOIN    logs l
ON      l.deviceid = q.deviceid
        AND l.poll_date = q.md

我想提取设备的最后一个条目,pollDate,status。例如

设备ID、轮询日期、状态

2010-95-06 10:53:281

3,2010-95-06 10:26:28,1


我尝试运行以下查询,但distinct只选择第一个记录,而不是最新的记录

SELECT DISTINCT deviceId, pollDate, status
FROM logs
GROUP By deviceId
ORDER BY pollDate DESC

那么,你能帮我从表中提取最新的条目吗?谢谢。

如果
(设备ID,投票日期)
是唯一的,您可以执行以下操作:

SELECT  *
FROM    (
        SELECT  deviceid, MAX(poll_date) AS md
        FROM    logs
        GROUP BY
                deviceid
        ) q
JOIN    logs l
ON      l.deviceid = q.deviceid
        AND l.poll_date = q.md
如果
(deviceID,poll\u date)
是唯一的,则可以执行以下操作:

SELECT  *
FROM    (
        SELECT  deviceid, MAX(poll_date) AS md
        FROM    logs
        GROUP BY
                deviceid
        ) q
JOIN    logs l
ON      l.deviceid = q.deviceid
        AND l.poll_date = q.md