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180. 连续出现的数字

English Version

题目描述

表：Logs

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| num         | varchar |
+-------------+---------+
id 是这个表的主键。

 

编写一个 SQL 查询，查找所有至少连续出现三次的数字。

返回的结果表中的数据可以按 任意顺序 排列。

查询结果格式如下面的例子所示：

 

示例 1:

输入：
Logs 表：
+----+-----+
| Id | Num |
+----+-----+
| 1  | 1   |
| 2  | 1   |
| 3  | 1   |
| 4  | 2   |
| 5  | 1   |
| 6  | 2   |
| 7  | 2   |
+----+-----+
输出：
Result 表：
+-----------------+
| ConsecutiveNums |
+-----------------+
| 1               |
+-----------------+
解释：1 是唯一连续出现至少三次的数字。

解法

SQL

select distinct(Num) as ConsecutiveNums from Logs Curr where
    Num = (select Num from Logs where id = Curr.id - 1) and
    Num = (select Num from Logs where id = Curr.id - 2)

# Write your MySQL query statement below
SELECT DISTINCT l1.num AS ConsecutiveNums
FROM
    logs AS l1,
    logs AS l2,
    logs AS l3
WHERE
    l1.id = l2.id - 1
    AND
    l2.id = l3.id - 1
    AND
    l1.num = l2.num
    AND
    l2.num = l3.num