Mysql 按设备ID查询最后一个条目组
我的数据库表日志如下所示: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,
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