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  • 电影sql问题

    看的次数多 或者 评分高

    每个用户最喜欢哪个类型的电影

    row_number()

    ratings表中一个电影出现几次?

    一个电影有几种类型?

    类型在movies   评分或者观看次数ratings

    movies join ratings

    //将类型炸开

    select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx;//这是炸开的表

    //观看的次数  类型  id

    select count(*) cnt,r.uid,t.lx

    (select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx ) t,ratings r

    where r.mid=t.mid  

    group by r.uid,t.lx

    //开窗函数

    select t2.uid,t2.lx

    from

    (select row_number() over (partition by t1.uid order by t1.cnt desc) rn,t1.uid,t1.lx

    from

    (select count(*) cnt,r.uid,t.lx

    (select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx ) t,ratings r

    where r.mid=t.mid  

    group by r.uid,t.lx) t1)t2

    where t2.rn=1;

    //uid lx  这个用户最喜欢的类型

    ======================================================================================

    lx m1 m2 m3 

    //电影表

    select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx

    select count(*) cnt,t.lx,r.mid

    (select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx) t,ratings r

    where r.mid=t.mid

    group t.lx=r.mid; 

    select row_number() overs (partition by t1.lx order by t1.cnt desc),t1.lx,t1.mid

    (select count(*) cnt,t.lx,r.mid

    (select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx) t,ratings r

    where r.mid=t.mid

    group t.lx=r.mid) t1

    //

    select t2.lx,t2.mid

    from

    (select row_number() overs (partition by t1.lx order by t1.cnt desc) rn,t1.lx,t1.mid

    (select count(*) cnt,t.lx,r.mid

    (select mid,mname,lx from movies lateral view explode(split(type,"\|")) types as lx) t,ratings r

    where r.mid=t.mid

    group t.lx=r.mid) t1) t2

    每个类型最受欢迎的前三个电影

    类型==类型

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  • 原文地址:https://www.cnblogs.com/JBLi/p/10857553.html
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