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