这篇文章给大家分享的是有关mysql中如何查询前50%的数据的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。

实验环境:

createtablet(cint);
insertintotvalues
(15),(7),(9),(10),(7),(8),(20),(16),(9),(19),
(14),(10),(11),(10),(10),(12),(7),(10),(7),(9);
commit;



c 等于10,7,9的数量有 11个，超过了半数。
超过半数的 item信息。

通用方式,不依赖具体数据库。


select t5.*,t6.*,ifnull(round(t5.sumtotal/t6.total,2),0) result from (

select t3.rn,t3.total,t3.c,sum(ifnull(t4.total,0)) sumtotal from (

select

t1.*,

(

select count(case when t2.total>t1.total then 1 when t2.total=t1.total and t2.c<t1.c then 1 else null end)+1 from (

select c,count(*) total from t group by c

) t2

) rn

from(

select c,count(*) total from t group by c order by total desc ,c

) t1

) t3

left join(

select

t1.*,

(

select count(case when t2.total>t1.total then 1 when t2.total=t1.total and t2.c<t1.c then 1 else null end)+1 from (

select c,count(*) total from t group by c

) t2

) rn

from(

select c,count(*) total from t group by c order by total desc ,c

) t1

) t4 on (t3.rn> t4.rn)

group by t3.rn,t3.total,t3.c

) t5

left join(

select count(*) total from t

) t6 on(1=1)

where ifnull(round(t5.sumtotal/t6.total,2),0)<=0.5;

查询结果:


绑定MySQL的实现

select * from (

select t3.*,case when result<=0.5 then 1 when result>0.5 and @b=-1 then @b:=1 else null end r from (

select t1.*,round((@a:=@a+t1.total)/t2.total,2) result from (

select c,count(*) total from t,(select @a:=0,@b:=-1) vars group by c order by 2 desc

) t1

left join(

select count(*) total from t

) t2 on(1=1)

) t3 order by result

) t4 where r=1;


结果:


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