[英]How to have a query add a ranking by a group of values in DESCENDING order
我有一張視頻表
表格 :“ id”,“ video_key,“ week”
值 :(1,12345,2016-01-03),(2,23456,2016-01-03),(3,3456,2015-01-03),等等...
“周”總是會有些周日日期,並在“周”可以有任意數量的視頻。
我正在嘗試提出一個查詢,該查詢按“周” DESC排序視頻,並具有降序 ( 降級 ?)的排名。 我可以使用以下內容以遞增的順序獲取視頻-但這不是我需要的結果。
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
這返回類似
[id,video_key,week,rank,...] 1,12345,2016-01-03,1,.. 2,23456,2016-01-03,2,.. 3,3456,2016-01-03,3,....
但是我實際上需要它
[id,video_key,week,rank,...] 3,3456,2016-01-03,1,.. 2,23456,2016-01-03,2,.. 1,12345,2015-01-03,3
我的想法是,我需要進行子查詢以獲取每周的視頻數(*),然后執行以下操作:
CASE WHEN @week = week
THEN @weekly_count_of_videos:=@weekly_count_of_videos -1
//....etc
我希望這一切都說得通....感謝您提出的任何提示或指點。
基於戈登·利諾夫的答案的更新查詢
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
只需使您的查詢成為子查詢並按外部查詢順序即可:
select t.*
from (<your query>
) t
order by rank desc;
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