[英]sql join Query the database ,There is no desired result,
我的需求是:从数据库查询最新数据,按照时间字段为标准,查询alarmtime此字段,但Alarmtime <time执行sql:
SELECT
c.entryTime AS alarmtime ,
a.time AS time
FROM (
SELECT
t.DB33,
MAX( t.Time ) AS time,
t.Stream,
t.Coil,
t.`View`
FROM (
SELECT DB33, Time, Stream, Coil, `View`
FROM running_check
ORDER BY id DESC
LIMIT 1000 ) as t
GROUP BY t.DB33 ) AS a
LEFT JOIN (
select cameraID,cameraName
from monitor_link_info) as b ON a.db33 = b.cameraID
LEFT JOIN (
SELECT entryTime, cameraID
FROM result_video_v2
ORDER BY id DESC
limit 1000 ) AS c ON a.db33 = c.cameraId
GROUP BY a.db33, b.cameraName
ORDER BY a.time DESC, alarmtime DESC
执行结果不友好,请立即查看图像时间列而不是我想要的,因为他没有改变。
SELECT
c.entryTime AS alarmtime ,
a.time AS TIME
FROM
(
SELECT DB33, MAX(TIME) TIME, Stream, Coil, `View`
FROM running_check
ORDER BY id DESC
GROUP BY t.DB33
LIMIT 1000
) AS a
LEFT JOIN
(
SELECT cameraID,cameraName
FROM monitor_link_info
GROUP BY cameraID
LIMIT 1000
) AS b ON (a.db33 = b.cameraID)
LEFT JOIN (
SELECT entryTime, cameraID
FROM result_video_v2
GROUP BY cameraID
ORDER BY id DESC
LIMIT 1000
) AS c ON (a.db33 = c.cameraID)
GROUP BY a.db33, b.cameraName
ORDER BY a.time DESC, c.entryTime DESC
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