【LeetCode】601.体育馆的人流量

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601.体育馆的人流量

X 市建了一个新的体育馆，每日人流量信息被记录在这三列信息中：序号(id)、日期(date)、人流量(people)。

请编写一个查询语句，找出高峰期时段，要求连续三天及以上，并且每天人流量均不少于100。

用到的表和数据SQL：

Create table If Not Exists stadium (id int,date DATE NULL, people int);
Truncate table stadium;
insert into stadium (id, date, people) values('1', '2017-01-01', '10');
insert into stadium (id, date, people) values('2', '2017-01-02', '109');
insert into stadium (id, date, people) values('3', '2017-01-03', '150');
insert into stadium (id, date, people) values('4', '2017-01-04', '99');
insert into stadium (id, date, people) values('5', '2017-01-05', '145');
insert into stadium (id, date, people) values('6', '2017-01-06', '1455');
insert into stadium (id, date, people) values('7', '2017-01-07', '199');
insert into stadium (id, date, people) values('8', '2017-01-08', '188'); 

答案：

此题主要还是靠拆分看题，相当于分成三部分，分成三个表s1,s2,s3的组合判断，

（1）s1.id-s2.id=1,s2.id-s3.id=1，相当于s3 s2 s1 的顺序三个连续的

（2）s2.id-s1.id=1,s1.id-s3.id=1，相当于s3 s1 s2 的顺序三个连续的

（3）s3.id-s2.id=1,s2.id-s1.id=1，相当于s1 s2 s3 的顺序三个连续的

具体SQL语句如下：

select distinct s1.*
from stadium s1, stadium s2, stadium s3
where s1.people >= 100 and s2.people>= 100 and s3.people >= 100
and
(
    (s1.id - s2.id = 1 and s2.id - s3.id =1)
   or
   (s2.id - s1.id = 1 and s1.id - s3.id =1) 
   or
   (s3.id - s2.id = 1 and s2.id - s1.id = 1) 
) order by s1.id;

写的比较粗糙，有不理解的可以扫描二维码加QQ群找我解答。