通过不按日期顺序返回结果进行分组

Question

在我的项目中，当用户观看视频时，它将被插入到用于存储观看的电影详细信息的表中。

我正在使用以下查询按最新记录的顺序获取当前用户观看的电影。如果用户多次观看视频，则应该只返回其中最新的记录。

我正在使用以下查询。

SELECT vm.watched_on,vm.movie_id,cp.channel_id,
v.title, v.videothumbnail, v.views, v.likes, v.length, v.videoid,
cp.title as videotitle, cv.thumbnail,cv.views as cvviews,cv.likes as cvlikes, cv.id,cp.starttime,cp.endtime,vm.videotype
FROM viewedmovies as vm
LEFT JOIN video as v
ON (vm.movie_id=v.videoid AND vm.user_id=1 AND vm.videotype=1 and v.permission!=-1)
LEFT JOIN channel_videos as cv
ON (vm.movie_id=cv.id AND vm.user_id=1 AND (vm.videotype=0 or vm.videotype=2))
LEFT JOIN channel_programmes as cp
ON (vm.movie_id=cp.programme_source AND (vm.videotype=0 or vm.videotype=2) AND cp.status!=-1) 
where vm.user_id=1 GROUP BY vm.user_id, vm.movie_id, vm.videotype
ORDER BY vm.watched_on desc
LIMIT 6

视频存储在两个表中：如果 viewedmovies 中的 videotype 为 1，它将从视频表中查询，如果 videotype 为 0 ，它将从 channel_programmes 和 channel_videos 中查询。此查询正在返回结果，但不是按日期顺序。

http://sqlfiddle.com/#!2/0c382/1

谁能帮我解决这个问题？提前致谢。

Answer 1

http://sqlfiddle.com/#!2/0c382/55

SELECT vm.watched_on,vm.movie_id,cp.channel_id,
v.title, v.videothumbnail, v.views, v.likes, v.length, v.videoid,
cp.title as videotitle, cv.thumbnail,cv.views as cvviews,cv.likes as cvlikes, cv.id,cp.starttime,cp.endtime,vm.videotype
FROM
(
     SELECT x.*
     FROM
     (
         SELECT user_id, movie_id, watched_on, videotype
         FROM viewedmovies
         ORDER BY watched_on DESC
     ) as x
     GROUP BY x.user_id, x.movie_id
) as vm
LEFT JOIN video as v
    ON (vm.movie_id=v.videoid AND vm.user_id=1 AND vm.videotype=1 and v.permission!=-1)
LEFT JOIN channel_videos as cv
    ON (vm.movie_id=cv.id AND vm.user_id=1 AND (vm.videotype=0 or vm.videotype=2))
LEFT JOIN channel_programmes as cp
    ON (vm.movie_id=cp.programme_source AND (vm.videotype=0 or vm.videotype=2) AND cp.status!=-1) 
WHERE vm.user_id=1 
ORDER BY vm.watched_on desc