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Formatted question description: https://leetcode.ca/all/601.html
601. Human Traffic of Stadium
Level
Hard
Description
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
:
+------+------------+-----------+
| 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:
+------+------------+-----------+
| 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
Suppose three consecutive rows in table are s1
, s2
and s3
respectively. Each such row has people
at least 100. Select all the fields of s1
, where s1
can be at any position among s1
, s2
and s3
.
# Write your MySQL query statement below
select distinct s1.* from stadium s1, stadium s2, stadium s3
where ((s1.id = s2.id - 1 and s2.id = s3.id - 1) or
(s1.id = s2.id + 1 and s1.id = s3.id - 1) or
(s1.id = s3.id + 1 and s2.id = s3.id - 1))
and (s1.people >= 100 and s2.people >= 100 and s3.people >= 100)
order by s1.id;