LeetCode 180：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.

select DISTINCT(a.Num)
from Logs a, Logs b, Logs c
  where a.Id+1=b.Id and a.Id+2=c.Id and a.Num=b.Num and b.Num=c.Num;