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。
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');
拆分看题,三表自联查,每个的人数都大于100,
(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
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