我遇到以下SQL查询和MySQL的问题
SELECT
id, cpid, label, cpdatetime
FROM
mytable AS a
WHERE
id NOT IN
(
SELECT
id
FROM
mytable AS b
WHERE
a.label = b.label
AND
a.cpdatetime > b.cpdatetime
)
AND
label LIKE 'CB%'
AND
cpid LIKE :cpid
GROUP BY label
ORDER BY cpdatetime ASC
表格看起来像这样
1 | 170.1 | CB55 | 2013-01-01 00:00:01
2 | 135.5 | CB55 | 2013-01-01 00:00:02
3 | 135.6 | CB59 | 2013-01-01 00:00:03
4 | 135.5 | CM43 | 2013-01-01 00:00:04
5 | …