【MySQL】ANY函数的巧用（筛选字段＞ ANY(语句) 和筛选字段＜ ANY(语句)）

力扣题

1、题目地址

1355. 活动参与者

2、模拟表

表：Friends

Column Name	Type
id	int
name	varchar
activity	varchar

id 是朋友的 id，并且在 SQL 中，是该表的主键
name 是朋友的名字
activity 是朋友参加的活动的名字

表：Activities

Column Name	Type
id	int
name	varchar

在 SQL 中，id 是该表的主键
name 是活动的名字

3、要求

找出那些既没有最多，也没有最少参与者的活动的名字。

Activities 表中的任意活动都有在 Friends 中参与过。

可以以任何顺序返回结果。

下面是返回结果格式的例子。

示例 1：

输入：

Friends 表：

id	name	activity
1	Jonathan D.	Eating
2	Jade W.	Singing
3	Victor J.	Singing
4	Elvis Q.	Eating
5	Daniel A.	Eating
6	Bob B.	Horse Riding

Activities 表：

id	name
1	Eating
2	Singing
3	Horse Riding

输出：

activity
Singing

解释：
Eating 活动有三个人参加, 是最多人参加的活动 (Jonathan D. , Elvis Q. and Daniel A.)
Horse Riding 活动有一个人参加, 是最少人参加的活动 (Bob B.)
Singing 活动有两个人参加 (Victor J. and Jade W.)

4、代码编写

我的写法

代码

SELECT DISTINCT activity
FROM (SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS numFROM Friends
) AS two
WHERE num != (SELECT MAX(num)FROM (SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS numFROM Friends) AS one
) 
AND num != (SELECT MIN(num)FROM (SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS numfrom Friends) AS one
)

代码分析

1、先将出现次数算出来

SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS num
FROM Friends

| id | name        | activity     | num |
| -- | ----------- | ------------ | --- |
| 1  | Jonathan D. | Eating       | 3   |
| 4  | Elvis Q.    | Eating       | 3   |
| 5  | Daniel A.   | Eating       | 3   |
| 6  | Bob B.      | Horse Riding | 1   |
| 2  | Jade W.     | Singing      | 2   |
| 3  | Victor J.   | Singing      | 2   |

2、之后再把最高次数和最低次数过滤掉

WHERE num != (SELECT MAX(num)FROM (SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS numFROM Friends) AS one
) 
AND num != (SELECT MIN(num)FROM (SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS numfrom Friends) AS one
)

网友巧用 ANY 函数写法

代码

SELECT activity
FROM Friends
GROUP BY activity
HAVING COUNT(*) < ANY(SELECT COUNT(activity) OVER (PARTITION BY activity) FROM Friends) 
AND COUNT(*) > ANY(SELECT COUNT(activity) OVER (PARTITION BY activity) FROM Friends)

代码分析

1、首先要求里面我们是要查询出活动名（activity），可以直接使用分组（GROUP BY）取出每个都单一，不用去重，之后就要进行过滤操作

SELECT activity
FROM Friends
GROUP BY activity

2、过滤操作，我们知道使用 GROUP BY 之后，使用 count(*) 可以获取对应分组里面出现的次数，我们只要满足让次数不为全部的最大和全部的最小即可

SELECT COUNT(activity) OVER (PARTITION BY activity) FROM Friends

我使用 SELECT *, COUNT(activity) OVER (PARTITION BY activity) AS num FROM Friends 执行让大家看明显一些

| id | name        | activity     | num |
| -- | ----------- | ------------ | --- |
| 1  | Jonathan D. | Eating       | 3   |
| 4  | Elvis Q.    | Eating       | 3   |
| 5  | Daniel A.   | Eating       | 3   |
| 6  | Bob B.      | Horse Riding | 1   |
| 2  | Jade W.     | Singing      | 2   |
| 3  | Victor J.   | Singing      | 2   |

可以看出出现次数最大值是3，最小值是1

3、这里就可以使用到 ANY 函数，上面的 < ANY 表示，次数小于右边的最大值（3），下面 > ANY 表示，次数大于右边的最小值

COUNT(*) < ANY(SELECT COUNT(activity) OVER (PARTITION BY activity) FROM Friends) 
AND COUNT(*) > ANY(SELECT COUNT(activity) OVER (PARTITION BY activity) FROM Friends)