Links

Exercise 6:601.Human Traffic of Stadium

1.Description

Table: Stadium
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| visit_date | date |
| people | int |
+---------------+---------+
visit_date is the primary key for this table.
Each row of this table contains the visit date and visit id to the stadium with the number of people during the visit.
No two rows will have the same visit_date, and as the id increases, the dates increase as well.
Write an SQL query to display the records with three or more rows with consecutive id's, and the number of people is greater than or equal to 100 for each.
Return the result table ordered by visit_date in ascending order.
The query result format is in the following example.
Example 1:
Input:
Stadium table:
+------+------------+-----------+
| 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 | 2017-01-09 | 188 |
+------+------------+-----------+
Output:
+------+------------+-----------+
| id | visit_date | people |
+------+------------+-----------+
| 5 | 2017-01-05 | 145 |
| 6 | 2017-01-06 | 1455 |
| 7 | 2017-01-07 | 199 |
| 8 | 2017-01-09 | 188 |
+------+------------+-----------+
Explanation:
The four rows with ids 5, 6, 7, and 8 have consecutive ids and each of them has >= 100 people attended. Note that row 8 was included even though the visit_date was not the next day after row 7.
The rows with ids 2 and 3 are not included because we need at least three consecutive ids.

2.Create Table and insert into values

create table if not exists leetcode.ex_601_stadium
(
id int,
visit_date date,
people int
) stored as orc ;
​
INSERT INTO table leetcode.ex_601_stadium VALUES
('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' ,' 2017-01-09' ,'188' )
  1. 1.
    Note that this question requires consecutive IDs to be returned. In real business, we usually care about the consecutive days because consecutive login or use can reflect user loyalty for your product.
  2. 2.
    For the consecutive problem, The first idea that comes to our mind is to use lead() or lag() window functions.
​