180. 连续出现的数字

题目

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：

Logs 表：

Id	Num
1	1
2	1
3	1
4	2
5	1
6	2
7	2

Result 表：

ConsecutiveNums
1

1 是唯一连续出现至少三次的数字。

题解

解法1解法2

sql

-- 记录连续即可
SELECT DISTINCT `t`.`Num` AS `ConsecutiveNums`
FROM (
         SELECT CASE
                    WHEN @`preValue` = `l`.`Num`
                        THEN @`cnt` := @`cnt` + 1
                    WHEN `l`.`Num` IS NOT NULL AND @`preValue` := `l`.`Num`
                        THEN @`cnt` := 1
                END AS `cnt`,
                `l`.`Num`
         FROM `Logs` `l`,
              (SELECT @`preValue` := NULL, @`cnt` := 0) `r`
     ) `t`
WHERE `t`.`cnt` >= 3;

-- 记录连续即可
SELECT DISTINCT `t`.`Num` AS `ConsecutiveNums`
FROM (
         SELECT CASE
                    WHEN @`preValue` = `l`.`Num`
                        THEN @`cnt` := @`cnt` + 1
                    WHEN `l`.`Num` IS NOT NULL AND @`preValue` := `l`.`Num`
                        THEN @`cnt` := 1
                END AS `cnt`,
                `l`.`Num`
         FROM `Logs` `l`,
              (SELECT @`preValue` := NULL, @`cnt` := 0) `r`
     ) `t`
WHERE `t`.`cnt` >= 3;

sql

-- 必须满足id连续
SELECT DISTINCT `l1`.`Num` AS `ConsecutiveNums`
FROM `Logs` `l1`
         INNER JOIN `Logs` `l2` ON `l1`.`Id` = `l2`.`id` - 1 AND `l1`.`Num` = `l2`.`Num`
         INNER JOIN `Logs` `l3` ON `l1`.`Id` = `l3`.`Id` - 2 AND `l1`.`Num` = `l3`.`Num`

-- 必须满足id连续
SELECT DISTINCT `l1`.`Num` AS `ConsecutiveNums`
FROM `Logs` `l1`
         INNER JOIN `Logs` `l2` ON `l1`.`Id` = `l2`.`id` - 1 AND `l1`.`Num` = `l2`.`Num`
         INNER JOIN `Logs` `l3` ON `l1`.`Id` = `l3`.`Id` - 2 AND `l1`.`Num` = `l3`.`Num`

180. 连续出现的数字 ​

题目 ​

题解 ​

180. 连续出现的数字

题目

题解