[英]How to have a query add a ranking by a group of values in DESCENDING order
I have a table of videos 我有一张视频表
table : 'id', 'video_key, 'week' 表格 :“ id”,“ video_key,“ week”
values : (1, 12345, 2016-01-03), (2, 23456, 2016-01-03), (3, 3456, 2015-01-03), etc... 值 :(1,12345,2016-01-03),(2,23456,2016-01-03),(3,3456,2015-01-03),等等...
The 'week' will always be some Sunday date, and each 'week' can have any number of videos. “周”总是会有些周日日期,并在“周”可以有任意数量的视频。
I'm trying to come up with a query that orders the videos by 'week' DESC, and has a descending (decremented?) ranking. 我正在尝试提出一个查询,该查询按“周” DESC排序视频,并具有降序 ( 降级 ?)的排名。 I'm able to use the following to get videos in incremented ranked order - but this isn't the result I need.
我可以使用以下内容以递增的顺序获取视频-但这不是我需要的结果。
SELECT tt.*, rank FROM ( SELECT t.*, @week:=
CASE WHEN @week = week
THEN @rank:=@rank +1
ELSE @rank:=1
END rank,
@week:=t.week
FROM video_table t ,
(SELECT @rank:=0,@week:=0) r
ORDER BY week DESC, id ASC
) tt
This returns something like 这返回类似
[id,video_key,week,rank,...] 1,12345,2016-01-03,1,.. 2,23456,2016-01-03,2,.. 3,3456,2016-01-03,3,....
But I actually need it to be 但是我实际上需要它
[id,video_key,week,rank,...] 3,3456,2016-01-03,1,.. 2,23456,2016-01-03,2,.. 1,12345,2015-01-03,3
My thought is that I need to do a subquery to get the count(*) of videos for each week, and then do something like: 我的想法是,我需要进行子查询以获取每周的视频数(*),然后执行以下操作:
CASE WHEN @week = week
THEN @weekly_count_of_videos:=@weekly_count_of_videos -1
//....etc
I hope this all makes sense .... thanks for any tips, or pointers to get this going. 我希望这一切都说得通....感谢您提出的任何提示或指点。
UPDATED QUERY based on Gordon Linoff's answer 基于戈登·利诺夫的答案的更新查询
SELECT t3.* FROM (SELECT t2.* FROM ( SELECT t1.*, @week:= CASE WHEN @week = week THEN @rank:=@rank +1 ELSE @rank:=1 END rank, @week:=t1.week FROM video_table t1 , (SELECT @rank:=0,@week:=0) r ORDER BY week DESC, id ASC ) t2) t3 order by week DESC, rank desc
Just make your query a subquery and order by the outer one: 只需使您的查询成为子查询并按外部查询顺序即可:
select t.*
from (<your query>
) t
order by rank desc;
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