Human Traffic of Stadium
Desicription
X city built a new stadium, each day many people visit it and the stats are saved as these columns: id, visit_date, people
Please write a query to display the records which have 3 or more consecutive rows and the amount of people more than 100(inclusive).
For example, the table stadium:
代码语言：javascript复制 ------ ------------ -----------
| id | visit_date | people |
------ ------------ -----------
| 1 | 2017-01-01 | 10 |
| 2 | 2017-01-02 | 109 |
| 3 | 2017-01-03 | 150 |
| 4 | 2017-01-04 | 99 |
| 5 | 2017-01-05 | 145 |
| 6 | 2017-01-06 | 1455 |
| 7 | 2017-01-07 | 199 |
| 8 | 2017-01-08 | 188 |
------ ------------ ----------- For the sample data above, the output is:
代码语言：javascript复制 ------ ------------ -----------
| id | visit_date | people |
------ ------------ -----------
| 5 | 2017-01-05 | 145 |
| 6 | 2017-01-06 | 1455 |
| 7 | 2017-01-07 | 199 |
| 8 | 2017-01-08 | 188 |
------ ------------ ----------- Note: Each day only have one row record, and the dates are increasing with id increasing.
Solution
代码语言：javascript复制select s1.* from stadium as s1, stadium as s2, stadium as s3
where
((s1.id = s2.id - 1 and s1.id = s3.id - 2) or
(s1.id = s2.id 1 and s1.id = s3.id - 1) or
(s1.id = s2.id 2 and s1.id = s3.id 1)) and
(s1.people >= 100 and s2.people >= 100 and s3.people >= 100)
group by s1.id;
