体系化学习SQL，请到牛客经典高频面试题库，参加实训，提高你的SQL技能吧~

https://www.nowcoder.com/link/pc_csdncpt_itbd_sql

前言

SQL每个人都要用，但是用来衡量产出的并不是SQL本身，你需要用这个工具，去创造其它的价值。

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🐴 SQL1 各个视频的平均完播率

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
  (101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:30', 0, 1, 1, null),
  (102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:24', 0, 0, 1, null),
  (103, 2001, '2021-10-01 11:00:00', '2021-10-01 11:00:34', 0, 1, 0, 1732526),
  (101, 2002, '2021-09-01 10:00:00', '2021-09-01 10:00:42', 1, 0, 1, null),
  (102, 2002, '2021-10-01 11:00:00', '2021-10-01 11:00:30', 1, 0, 1, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
  (2001, 901, '影视', 30, '2021-01-01 7:00:00'),
  (2002, 901, '美食', 60, '2021-01-01 7:00:00'),
  (2003, 902, '旅游', 90, '2021-01-01 7:00:00');
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📖 需求

问题：计算2021年里有播放记录的每个视频的完播率(结果保留三位小数)，并按完播率降序排序
注：视频完播率是指完成播放次数占总播放次数的比例。简单起见，
结束观看时间与开始播放时间的差>=视频时长时，视为完成播放。
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🍌🍌 答案

select a.video_id,
round(sum(case when timestampdiff(second,b.start_time,b.end_time)>=a.duration 
          then 1 else 0 end)/count(b.uid),3)
as avg_com_play_rate
from tb_video_info a join tb_user_video_log b on a.video_id=b.video_id
where YEAR(b.start_time) = 2021
group by a.video_id
order by avg_com_play_rate desc
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🐴 SQL2 平均播放进度大于60%的视频类别

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
  (101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:30', 0, 1, 1, null),
  (102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:21', 0, 0, 1, null),
  (103, 2001, '2021-10-01 11:00:50', '2021-10-01 11:01:20', 0, 1, 0, 1732526),
  (102, 2002, '2021-10-01 11:00:00', '2021-10-01 11:00:30', 1, 0, 1, null),
  (103, 2002, '2021-10-01 10:59:05', '2021-10-01 11:00:05', 1, 0, 1, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
  (2001, 901, '影视', 30, '2021-01-01 7:00:00'),
  (2002, 901, '美食', 60, '2021-01-01 7:00:00'),
  (2003, 902, '旅游', 90, '2020-01-01 7:00:00');
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📖 需求

问题：计算各类视频的平均播放进度，将进度大于60%的类别输出。
注：
播放进度=播放时长÷视频时长*100%，当播放时长大于视频时长时，播放进度均记为100%。
结果保留两位小数，并按播放进度倒序排序。
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🍌🍌 答案

select
tag,
concat(
    ROUND(
        avg(
            if(
                timestampdiff(second,start_time,end_time)>=duration,
                1,timestampdiff(second,start_time,end_time)/duration
               )
            )*100
            ,2)
    ,'%') avg_play_progress
from 
tb_user_video_log a join tb_video_info b
on a.video_id=b.video_id
group by b.tag
having avg(
            if(
                timestampdiff(second,start_time,end_time)>=duration,
                1,timestampdiff(second,start_time,end_time)/duration
               )
    )>0.6
order by avg_play_progress desc
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🐴 SQL3 每类视频近一个月的转发量/率

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
   (101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:20', 0, 1, 1, null)
  ,(102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:15', 0, 0, 1, null)
  ,(103, 2001, '2021-10-01 11:00:50', '2021-10-01 11:01:15', 0, 1, 0, 1732526)
  ,(102, 2002, '2021-09-10 11:00:00', '2021-09-10 11:00:30', 1, 0, 1, null)
  ,(103, 2002, '2021-10-01 10:59:05', '2021-10-01 11:00:05', 1, 0, 0, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
   (2001, 901, '影视', 30, '2021-01-01 7:00:00')
  ,(2002, 901, '美食', 60, '2021-01-01 7:00:00')
  ,(2003, 902, '旅游', 90, '2020-01-01 7:00:00');
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📖 需求

问题：统计在有用户互动的最近一个月（按包含当天在内的近30天算，
比如10月31日的近30天为10.2~10.31之间的数据）中，每类视频的转发量和转发率（保留3位小数）。
注：转发率＝转发量÷播放量。结果按转发率降序排序。
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🍌🍌 答案

select b.tag, sum(if_retweet) retweet_cnt,  
round(sum(if_retweet)/count(1),3) retweet_rate from
tb_user_video_log a
left join  tb_video_info b
on a.video_id = b.video_id
where DATEDIFF(DATE((select max(start_time) from tb_user_video_log)) ,
               DATE(start_time)) <= 29
group by b.tag
order by 2 desc
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🐴 SQL4 每个创作者每月的涨粉率及截止当前的总粉丝量

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
   (101, 2001, '2021-09-01 10:00:00', '2021-09-01 10:00:20', 0, 1, 1, null)
  ,(105, 2002, '2021-09-10 11:00:00', '2021-09-10 11:00:30', 1, 0, 1, null)
  ,(101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:20', 1, 1, 1, null)
  ,(102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:15', 0, 0, 1, null)
  ,(103, 2001, '2021-10-01 11:00:50', '2021-10-01 11:01:15', 1, 1, 0, 1732526)
  ,(106, 2002, '2021-10-01 10:59:05', '2021-10-01 11:00:05', 2, 0, 0, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
   (2001, 901, '影视', 30, '2021-01-01 7:00:00')
  ,(2002, 901, '影视', 60, '2021-01-01 7:00:00')
  ,(2003, 902, '旅游', 90, '2020-01-01 7:00:00')
  ,(2004, 902, '美女', 90, '2020-01-01 8:00:00');
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📖 需求

问题：计算2021年里每个创作者每月的涨粉率及截止当月的总粉丝量
注：
涨粉率=(加粉量 - 掉粉量) / 播放量。结果按创作者ID、总粉丝量升序排序。
if_follow-是否关注为1表示用户观看视频中关注了视频创作者，
为0表示此次互动前后关注状态未发生变化，为2表示本次观看过程中取消了关注。
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🍌🍌 答案

SELECT B.AUTHOR AS AUTHOR,DATE_FORMAT(A.start_time,'%Y-%m') AS MONTH ,
ROUND((COUNT(CASE WHEN A.if_follow=1 THEN 1 END ) - 
       COUNT(CASE WHEN A.if_follow=2 THEN 1 END ))/COUNT(1) ,3) 
       AS FANS_GROWTH_RATE,
sum(sum(case when A.if_follow = 1 then 1
         when A.if_follow = 2 then -1
         else 0 end) ) over (partition by B.author 
                             order by date_format(A.start_time,'%Y-%m')) 
                             fans_total
FROM tb_user_video_log A 
LEFT JOIN tb_video_info B 
ON A.VIDEO_ID=B.video_id
WHERE year(A.start_time)=2021
and year(A.end_time)=2021
GROUP BY B.AUTHOR,DATE_FORMAT(A.start_time,'%Y-%m')
ORDER BY AUTHOR,fans_total
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🐴 SQL5 国庆期间每类视频点赞量和转发量

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
   (101, 2001, '2021-09-24 10:00:00', '2021-09-24 10:00:20', 1, 1, 0, null)
  ,(105, 2002, '2021-09-25 11:00:00', '2021-09-25 11:00:30', 0, 0, 1, null)
  ,(102, 2002, '2021-09-25 11:00:00', '2021-09-25 11:00:30', 1, 1, 1, null)
  ,(101, 2002, '2021-09-26 11:00:00', '2021-09-26 11:00:30', 1, 0, 1, null)
  ,(101, 2002, '2021-09-27 11:00:00', '2021-09-27 11:00:30', 1, 1, 0, null)
  ,(102, 2002, '2021-09-28 11:00:00', '2021-09-28 11:00:30', 1, 0, 1, null)
  ,(103, 2002, '2021-09-29 11:00:00', '2021-09-29 11:00:30', 1, 0, 1, null)
  ,(102, 2002, '2021-09-30 11:00:00', '2021-09-30 11:00:30', 1, 1, 1, null)
  ,(101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:20', 1, 1, 0, null)
  ,(102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:15', 0, 0, 1, null)
  ,(103, 2001, '2021-10-01 11:00:50', '2021-10-01 11:01:15', 1, 1, 0, 1732526)
  ,(106, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:05', 2, 0, 1, null)
  ,(107, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:05', 1, 0, 1, null)
  ,(108, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:05', 1, 1, 1, null)
  ,(109, 2002, '2021-10-03 10:59:05', '2021-10-03 11:00:05', 0, 1, 0, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
   (2001, 901, '旅游', 30, '2020-01-01 7:00:00')
  ,(2002, 901, '旅游', 60, '2021-01-01 7:00:00')
  ,(2003, 902, '影视', 90, '2020-01-01 7:00:00')
  ,(2004, 902, '美女', 90, '2020-01-01 8:00:00');
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📖 需求

问题：统计2021年国庆头3天每类视频每天的近一周总点赞量和一周内最大单天转发量，
结果按视频类别降序、日期升序排序。假设数据库中数据足够多，
至少每个类别下国庆头3天及之前一周的每天都有播放记录。
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🍌🍌 答案

select t1.tag,t1.day,sum(t2.likes),max(t2.retweet)
FROM
(select t2.tag ,left(t1.start_time,10) day,
 sum(t1.if_like) as likes,sum(t1.if_retweet) as retweet
from tb_user_video_log t1 left join 
tb_video_info t2
on t1.video_id=t2.video_id
group by t2.tag,day) t1
left join 
(select t2.tag ,left(t1.start_time,10) day,
 sum(t1.if_like) as likes,sum(t1.if_retweet) as retweet
from tb_user_video_log t1 left join 
tb_video_info t2
on t1.video_id=t2.video_id
group by t2.tag,day) t2
on t1.tag=t2.tag
where TIMESTAMPDIFF(day,t2.day,t1.day)<7
and TIMESTAMPDIFF(day,t2.day,t1.day)>=0
and t1.day in ("2021-10-01","2021-10-02","2021-10-03")
group by t1.tag,t1.day

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🐴 SQL6 近一个月发布的视频中热度最高的top3视频

🚀 建表语句

DROP TABLE IF EXISTS tb_user_video_log, tb_video_info;
CREATE TABLE tb_user_video_log (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid INT NOT NULL COMMENT '用户ID',
    video_id INT NOT NULL COMMENT '视频ID',
    start_time datetime COMMENT '开始观看时间',
    end_time datetime COMMENT '结束观看时间',
    if_follow TINYINT COMMENT '是否关注',
    if_like TINYINT COMMENT '是否点赞',
    if_retweet TINYINT COMMENT '是否转发',
    comment_id INT COMMENT '评论ID'
) CHARACTER SET utf8 COLLATE utf8_bin;

CREATE TABLE tb_video_info (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    video_id INT UNIQUE NOT NULL COMMENT '视频ID',
    author INT NOT NULL COMMENT '创作者ID',
    tag VARCHAR(16) NOT NULL COMMENT '类别标签',
    duration INT NOT NULL COMMENT '视频时长(秒数)',
    release_time datetime NOT NULL COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_bin;

INSERT INTO tb_user_video_log(uid, video_id, start_time, end_time, if_follow, if_like, if_retweet, comment_id) VALUES
   (101, 2001, '2021-09-24 10:00:00', '2021-09-24 10:00:30', 1, 1, 1, null)
  ,(101, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:31', 1, 1, 0, null)
  ,(102, 2001, '2021-10-01 10:00:00', '2021-10-01 10:00:35', 0, 0, 1, null)
  ,(103, 2001, '2021-10-03 11:00:50', '2021-10-03 11:01:35', 1, 1, 0, 1732526)
  ,(106, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:04', 2, 0, 1, null)
  ,(107, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:06', 1, 0, 0, null)
  ,(108, 2002, '2021-10-02 10:59:05', '2021-10-02 11:00:05', 1, 1, 1, null)
  ,(109, 2002, '2021-10-03 10:59:05', '2021-10-03 11:00:01', 0, 1, 0, null)
  ,(105, 2002, '2021-09-25 11:00:00', '2021-09-25 11:00:30', 1, 0, 1, null)
  ,(101, 2003, '2021-09-26 11:00:00', '2021-09-26 11:00:30', 1, 0, 0, null)
  ,(101, 2003, '2021-09-30 11:00:00', '2021-09-30 11:00:30', 1, 1, 0, null);

INSERT INTO tb_video_info(video_id, author, tag, duration, release_time) VALUES
   (2001, 901, '旅游', 30, '2021-09-05 7:00:00')
  ,(2002, 901, '旅游', 60, '2021-09-05 7:00:00')
  ,(2003, 902, '影视', 90, '2021-09-05 7:00:00')
  ,(2004, 902, '影视', 90, '2021-09-05 8:00:00');
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📖 需求

问题：找出近一个月发布的视频中热度最高的top3视频。

注：
热度=(a*视频完播率+b*点赞数+c*评论数+d*转发数)*新鲜度；
新鲜度=1/(最近无播放天数+1)；
当前配置的参数a,b,c,d分别为100、5、3、2。
最近播放日期以end_time-结束观看时间为准，假设为T，则最近一个月按[T-29, T]闭区间统计。
结果中热度保留为整数，并按热度降序排序。
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🍌🍌 答案

select t1.video_id
,round(
((sum(case when timestampdiff(second,start_time,end_time)>=duration 
      then 1 else 0 end ))/count(*)*100
+sum(if_like)*5
+count(comment_id)*3
+sum(if_retweet)*2)
*
1/(DATEDIFF((select date(max(end_time)) from tb_user_video_log),
            date(max(end_time)))+1)
) as hot_index
from tb_user_video_log t1,tb_video_info t2
where t1.video_id=t2.video_id
and DATEDIFF(DATE((SELECT MAX(end_time) FROM tb_user_video_log)),
             DATE(release_time)) <= 29
group by t1.video_id
order by hot_index desc
limiT 3

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