Consecutive_Numbers.sql

/*
Consecutive Numbers
https://leetcode.com/problems/consecutive-numbers/

Write a SQL query to find all numbers that appear at least three times consecutively.

+----+-----+
| Id | Num |
+----+-----+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 1 |
| 6 | 2 |
| 7 | 2 |
+----+-----+
For example, given the above Logs table, 1 is the only number that appears consecutively for at least three times.

+-----------------+
| ConsecutiveNums |
+-----------------+
| 1 |
+-----------------+
*/

SELECT DISTINCT(l1.Num) AS ConsecutiveNums
FROM
 Logs l1, Logs l2, Logs l3
WHERE (
l1.Num=l2.NumANDl1.Id= (l2.Id+1) AND
l2.Num=l3.NumANDl2.Id= (l3.Id+1)
)