ROP 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');
学习链接:MySQL中的 UNIX_TIMESTAMP 函数使用总结(附详例)_sql unix_timestamp-CSDN博客
将数据转为时间戳
DATE 将value转换成'YYYY-MM-DD'格式
DATETIME 将value转换成'YYYY-MM-DD HH:MM:SS'格式
TIME 将value转换成'HH:MM:SS'格式
CHAR 将value转换成CHAR(固定长度的字符串)格式
SIGNED 将value转换成INT(有符号的整数)格式
UNSIGNED 将value转换成INT(无符号的整数)格式
DECIMAL 将value转换成FLOAT(浮点数)格式
BINARY 将value转换成二进制格式
保留小数位
CAST('9.0' AS DECIMAL) ->
DECIMAL(数值精度,小数点保留长度)
-- DECIMAL(10,2)可以存储最多具有8位整数和2位小数的数字
-- 精度与小数位数分别为10与2
-- 精度是总的数字位数,包括小数点左边和右边位数的总和
-- 小数位数是小数点右边的位数
SELECT
t3.video_id,
CAST(
COUNT(if(cha>=duration,1,null))*1.0 / COUNT(*) AS DECIMAL(16,3)
) AS avg_comp_play_rate
FROM
(
SELECT
t1.video_id,
cha,
duration
FROM
(
SELECT
video_id,
UNIX_TIMESTAMP(end_time) - UNIX_TIMESTAMP(start_time) AS cha
FROM
tb_user_video_log
WHERE
YEAR(start_time) = 2021
) AS t1
JOIN (
SELECT
video_id,
duration
FROM
tb_video_info
) AS t2
ON t1.video_id = t2.video_id
) t3
GROUP BY t3.video_id
ORDER BY avg_comp_play_rate DESC;
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');
select t3.tag as tag,CONCAT(avg_play_progress,'%') as avg_play_progress
from
(
SELECT
t1.tag,
CAST(
CAST(sum( if(cha>duration,1,CAST(cha/duration as DECIMAL(6,4))) )/ count(*) AS DECIMAL ( 4, 4 )) *100 as decimal(4,2)) AS avg_play_progress
FROM
(
SELECT
log.video_id,
tag,
UNIX_TIMESTAMP( end_time )- UNIX_TIMESTAMP( start_time ) AS cha
FROM
tb_user_video_log AS log
JOIN tb_video_info AS info ON log.video_id = info.video_id
) t1
JOIN ( SELECT tag, duration FROM tb_video_info ) AS t2 ON t1.tag = t2.tag
GROUP BY
t1.tag
HAVING avg_play_progress>60
order by avg_play_progress DESC
) as t3
number | 必需。要四舍五入的数字 |
decimals | 可选。number 要四舍五入的小数位数。 如果省略,则返回整数(无小数) |
SELECT DATEDIFF(day,'2008-12-29','2008-12-30') AS DiffDate
SELECT tag,SUM(if_retweet) retweet_cut,ROUND(SUM(if_retweet)/COUNT(start_time),3) retweet_rate
FROM tb_user_video_log a LEFT JOIN tb_video_info b ON a.video_id=b.video_id
WHERE DATEDIFF((SELECT MAX(start_time) FROM tb_user_video_log),start_time)<=29
GROUP BY tag
ORDER BY retweet_rate DESC;
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');
select author, `month`, round(fans_add_cnt / play_cnt, 3) as fans_growth_rate,
sum(fans_add_cnt) over(partition by author order by `month`) as total_fans
from (
select author,
DATE_FORMAT(start_time, "%Y-%m") as `month`,
sum(if(if_follow=2, -1, if_follow)) as fans_add_cnt,
count(1) as play_cnt
from tb_user_video_log
join tb_video_info USING(video_id)
where YEAR(start_time) = 2021
group by author, `month`
) as t_author_monthly_fans_play_cnt
order by author, total_fans;
函数解读:
函数分为两个部分
第一部分是函数名称,开窗函数的数量较少,只有11个窗口函数+聚合函数(所有聚合函数都可以用作开窗函数),根据函数性质,有的要写参数,有的不需要写参数;
第二部分是over语句,over()是必须要写的,里面有三个参数,都是非必须参数,根据需求选写:
1.第一个参数是 partition by +分组字段,将数据根据此字段分成多份,如果不加partition by参数,那会把整个数据当做一个窗口。
2.第二个参数是 order by +排序字段,每个窗口的数据要不要进行排序。
3.第三个参数 rows/range between 起始位置 and 结束位置,这个参数仅针对滑动窗口函数有用,是在当前窗口下分出更小的子窗口。
其中起始位置和结束位置可写: