601. Human Traffic of Stadium

2018-06-12  本文已影响0人  无敌的肉包

X city built a new stadium, each day many people visit it and the stats are saved as these columns: id, 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:

+------+------------+-----------+
| id   | 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:

+------+------------+-----------+
| id   | 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.


Answer:

select distinct s1.id, s1.date, s1.people
from stadium s1 inner join stadium s2 inner join stadium s3
on ((s2.id=s1.id-1 and s3.id-2=s2.id) or ( s2.id-1=s1.id and s3.id-2=s1.id) or ( s2.id=s1.id-2 and s3.id-1=s2.id))
where s1.people>=100 and s2.people>=100 and s3.people>=100 
order by s1.id
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