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MySQL实现ORALCE的row_number()over(partition by xx)功能_MySQL

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Release： 2016-06-01 13:07:59
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比如有个需求，要找出班级里每门课分数最高的学生（课程名称，分数，学生姓名），注意这里不是只取最高分，要把课程名称，分数，学生姓名都取出来！

在ORALCE里我们可以用ROW_NUMBER()OVER轻松实现，但是在mysql里就有点麻烦了，不过还是可以做的。

select course,score,name

from

(select

heyf_tmp.course,
heyf_tmp.score,
heyf_tmp.name,
@rownum:=@rownum+1,
if(@pdept=heyf_tmp.course,@rank:=@rank+1,@rank:=1) as rank,          -- 分组字段
@pdept:=heyf_tmp.course
from 
(select course,name,score
from temp_student_score
order by course,score desc                                           -- 分组字段，排序字段
) heyf_tmp ,

(select @rownum :=0,@pdept := null ,@rank:=0) a 

) a where rank=1

最后我们只用取出RANK=1的部分就可以了

source：php.cn
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