编写一个 SQL 查询，查找所有至少连续出现三次的数字。
+----+-----+
| Id | Num |
+----+-----+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 1 |
| 6 | 2 |
| 7 | 2 |
+----+-----+
例如，给定上面的 Logs 表， 1 是唯一连续出现至少三次的数字。
+-----------------+
| ConsecutiveNums |
+-----------------+
| 1 |
+-----------------+
来源：力扣（LeetCode）
select distinct a.Num as ConsecutiveNums from Logs a join Logs b on b.Id = a.Id+1 join Logs c on c.Id = a.Id+2 where a.Num = b.Num and b.Num=c.Num