180. Consecutive Numbers

Level: Medium; Apple, Adobe, Amazon

Question:

Table: Logs

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| num         | varchar |
+-------------+---------+
id is the primary key for this table.
id is an autoincrement column.

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

Return the result table in any order.

The query result format is in the following example.

Example 1:

Input: 
Logs table:
+----+-----+
| id | num |
+----+-----+
| 1  | 1   |
| 2  | 1   |
| 3  | 1   |
| 4  | 2   |
| 5  | 1   |
| 6  | 2   |
| 7  | 2   |
+----+-----+
Output:
 
+-----------------+
| ConsecutiveNums |
+-----------------+
| 1               |
+-----------------+
Explanation:
 1 is the only number that appears consecutively for at least three times.

My Solution:

select distinct(l1.num) as ConsecutiveNums
from Logs l1, Logs l2, Logs l3
where l1.id=l2.id-1 and l2.id=l3.id-1 and l1.num=l2.num and l2.num=l3.num