思路：
使用order by按照views欄位做乙個全域性排序即可，同時我們設定只顯示前10條。
**：select videoid, uploader, age, category, length, views, rate, ratings, comments
from gulivideo_orc order by views desc limit 10;
思路：
(2)我們需要按照類別group by聚合，然後count組內的videoid個數即可。
(4)最後按照熱度排序，顯示前10條。
**：select category_name as category, count(t1.videoid) as hot from
(select videoid,category_name from
gulivideo_orc lateral view explode(category) t_catetory as category_name) t1
group by t1.category_name order by hot desc limit 10;
思路：
(2)把這20條資訊中的category**出來(列轉行)
**：select category_name as category,count(t2.videoid) as hot_with_views from
(select videoid, category_name from
(select * from gulivideo_orc order by views desc limit 20) t1
lateral view explode(category) t_catetory as category_name) t2
group by category_name order by hot_with_views desc;
思路：
select * from gulivideo_orc order by views desc limit 50;
select explode(relatedid) as videoid from t1;
(select distinct(t2.videoid), t3.category from t2 inner join
gulivideo_orc t3 on t2.videoid = t3.videoid) t4 lateral view explode(category) t_catetory as category_name;
**： select category_name as category,count(t5.videoid) as hot from
(select videoid,category_name from
(select distinct(t2.videoid),t3.category from
(select explode(relatedid) as videoid from
(elect * from gulivideo_orc order by views desc limit 50) t1) t2
inner join
gulivideo_orc t3 on t2.videoid = t3.videoid) t4 lateral view explode(category) t_catetory as category_name) t5
group by category_name order by hot desc;
思路：
(2)向category展開的表中插入資料。
**： 建立表類別表：
create table gulivideo_category(
videoid string,uploader string,age int,categoryid string,length int,
views int,rate float,ratings int,comments int,relatedid array)
row format delimited
fields terminated by "\t"
collection items terminated by "&"
stored as orc;
向類別表中插入資料：
insert into table gulivideo_category
select videoid,uploader,age,categoryid,
length,views,rate,ratings,comments,relatedid
from
gulivideo_orc lateral view explode(category) catetory as categoryid;
統計music類別的top10（也可以統計其他）
select videoid, views from gulivideo_category
where categoryid = "music" order by views desc limit 10;
思路：
(2)按照ratings排序即可
**：select videoid,views,ratings from gulivideo_category
where categoryid = "music" order by ratings desc limit 10;
思路：
select * from gulivideo_user_orc order by videos desc limit 10;
(2)通過uploader欄位與gulivideo_orc表進行join，得到的資訊按照views**次數進行排序即可。
**： select t2.videoid,t2.views,t2.ratings,t1.videos,t1.friends
from (select * from gulivideo_user_orc order by videos desc limit 10) t1
join gulivideo_orc t2
on t1.uploader = t2.uploader order by views desc limit 20;
思路：
(1)先得到categoryid展開的表資料
(2)子查詢按照categoryid進行分割槽，然後分區內排序，並生成遞增數字，該遞增數字這一列起名為rank列
(3)通過子查詢產生的臨時表，查詢rank值小於等於10的資料行即可。
**： select t1.* from (select videoid,categoryid,views,
row_number() over(partition by categoryid order by views desc)
rank from gulivideo_category) t1 where rank <= 10;
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