180. 连续出现的数字

地址:https://leetcode-cn.com/problems/consecutive-numbers/

## 编写一个 SQL 查询，查找所有至少连续出现三次的数字。    
     示例：
    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               |
    +-----------------+
    
    
`解题思路`

1 自联

       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
       ;