Hive SQL 影評案例練習

一、資料準備

1、users.dat
資料格式：2::M::56::16::70072，
資料條數：共有6040條資料
對應欄位：UserID BigInt, Gender String, Age Int, Occupation String, Zipcode String
欄位解釋：用戶id，性別，年齡，職業，郵政編碼

2、movies.dat
資料格式：2::Jumanji (1995)::Adventure|Children’s|Fantasy，
資料條數：共有3883條資料
對應欄位：MovieID BigInt, Title String, Genres String
欄位解釋：電影ID，電影名字，電影型別

3、ratings.dat
資料格式：1::1193::5::978300760，
資料條數：共有1000209條資料
對應欄位：UserID BigInt, MovieID BigInt, Rating Double, Timestamped String
欄位解釋：用戶ID，電影ID，評分，評分時間戳

二、需求分析

1、正確建表，匯入資料（三張表，三份資料），并驗證是否正確

（1）創建表

create table t_user(
    userid bigint,        --用戶id
    gender string,        --性別
    age int,              --年齡
    occupation string,    --職業
    zipcode string)       --郵政編碼
row format serde 'org.apache.hadoop.hive.serde2.RegexSerDe' 
with serdeproperties('input.regex'='(.*)::(.*)::(.*)::(.*)::(.*)','output.format.string'='%1$s %2$s %3$s %4$s %5$s')
stored as textfile;

create table t_movie(
    movieid bigint,       --電影ID
    title string,         --電影名字
    genres string)        --電影型別
row format serde 'org.apache.hadoop.hive.serde2.RegexSerDe' 
with serdeproperties('input.regex'='(.*)::(.*)::(.*)','output.format.string'='%1$s %2$s %3$s')
stored as textfile;

create table t_rating(
    userid bigint,        --用戶ID
    movieid bigint,       --電影ID
    rating double,        --評分
    timestamped String)   --評分時間戳
row format serde 'org.apache.hadoop.hive.serde2.RegexSerDe' 
with serdeproperties('input.regex'='(.*)::(.*)::(.*)::(.*)','output.format.string'='%1$s %2$s %3$s %4$s')
stored as textfile;

（2）匯入資料

load data local inpath '/usr/mydir/data/users.dat' into table t_user;
load data local inpath '/usr/mydir/data/movies.dat' into table t_movie;
load data local inpath '/usr/mydir/data/ratings.dat' into table t_rating;

（3）驗證資料

select * from t_user;
select count(1) from t_user ;    --6040條資料

select * from t_movie;
select count(1) from t_movie ;    --3883條資料

select * from t_rating;
select count(1) from t_rating ;    --1000209條資料

user表：

movie表：

rating表：

2、求被評分次數最多的10部電影，并給出評分次數（電影名，評分次數）

SELECT 
    title,
    rating_count
FROM 
    (SELECT 
        movieid,
        COUNT(rating) rating_count
    from t_rating 
    group by movieid
    ) t1
left join t_movie t2
on t1.movieid = t2.movieid
order by rating_count DESC 
LIMIT 10;

3、分別求男性，女性當中評分最高的10部電影（性別，電影名，影評分），評分人數大于等于50

SELECT * from
    (SELECT 
        'M' as gender,
        title,
        AVG(rating) avg_rating,
        count(rating) count_rating
    from 
        (SELECT     --三張表關聯，拿到性別，電影名，影評分
            t2.gender,
            t3.title,
            t1.rating
        from t_rating t1
        left join t_user t2 on t1.userid = t2.userid 
        left join t_movie t3 on t1.movieid = t3.movieid
        where t2.gender = 'M' 
        ) t4
    group by title
    HAVING count_rating >= 50
    order by avg_rating DESC 
    LIMIT 10
    ) a
UNION ALL 
SELECT * from 
    (SELECT 
        'F' as gender,
        title,
        AVG(rating) avg_rating,
        count(rating) count_rating
    from 
        (SELECT     --三張表關聯，拿到性別，電影名，影評分
            t2.gender,
            t3.title,
            t1.rating
        from t_rating t1
        left join t_user t2 on t1.userid = t2.userid 
        left join t_movie t3 on t1.movieid = t3.movieid
        where t2.gender = 'F' 
        ) t4
    group by title
    HAVING count_rating >= 50
    order by avg_rating DESC 
    LIMIT 10
    ) b

4、求好片（評分>=4.0）最多的那個年份的最好看的10部電影

SELECT 
    title,
    avg_rating
from 
    (SELECT 
        t1.title,
        SUBSTRING(t1.title,-5,4) year,
        avg(t2.rating) avg_rating
    from t_movie t1
    left join t_rating t2
    on t1.movieid = t2.movieid
    where t2.rating >= 4
    group by t1.title
    ) t4
where year IN 
    (SELECT year 
    from
        (SELECT 
            year,
            COUNT(year) count_year
        from
            (SELECT 
                t1.title,
                SUBSTRING(t1.title,-5,4) year
            from t_movie t1
            left join t_rating t2
            on t1.movieid = t2.movieid
            where t2.rating >= 4
            group by t1.title
            ) t3
        group by year 
        order by count_year DESC 
        LIMIT 1) t5
    )
order by avg_rating DESC 
limit 10;

5、求1997年上映的電影中，評分最高的10部Comedy類電影

SELECT 
    title,
    genres,
    AVG(rating) avg_rating
from
    (SELECT 
        t1.title,
        substr(t1.title,-5,4) year,
        t1.genres,
        t2.rating
    from t_movie t1
    left join t_rating t2
    on t1.movieid = t2.movieid
    ) t3
where year = '1997' and genres LIKE '%Comedy%'
group by title,genres
order by avg_rating DESC 
LIMIT 10;

6、該影評庫中各種型別電影中評價最高的5部電影（型別，電影名，平均影評分）

SELECT 
    type,
    title
FROM 
    (SELECT 
        title,
        type,
        ROW_NUMBER() over(partition by type order by avg_rating DESC) rn
    from
        (SELECT 
            title,
            type,
            AVG(rating) avg_rating
        from 
            (select
                t2.genres,
                t2.title,
                t1.rating
            from t_rating t1
            left join t_movie t2 
            on t1.movieid =t2.movieid
            ) t3
        lateral view explode(split(t3.genres,"\\|")) tmp as type
        group by type,title
        ) t4
    )t5
where rn <= 5;

7、各年評分最高的電影型別（年份，型別，影評分）

with tmp as
(SELECT 
    title,
    type,            
    rating,
    movie_year
from 
    (select
        t2.genres,
        t2.title,
        t1.rating,
        SUBSTRING(t2.title,-5,4) as movie_year 
    from t_rating t1
    left join t_movie t2 
    on t1.movieid =t2.movieid
    ) t3
lateral view explode(split(t3.genres,"\\|")) tmp as type
)
    
select 
    movie_year,
    type,
    avg_rating 
from
    (select
        movie_year,
        type,
        avg_rating, 
        ROW_NUMBER() over(partition by movie_year order by avg_rating DESC) rn
    FROM 
        (select
            movie_year,
            type,
            AVG(rating) avg_rating 
        FROM tmp
        group by movie_year,type
        ) t1
    ) t2
where rn = 1;

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