619. Biggest Single Number--MAX()

最新推荐文章于 2025-03-05 07:15:00 发布

pepi_xxx

最新推荐文章于 2025-03-05 07:15:00 发布

阅读量848

点赞数

分类专栏： leetcode database

本文链接：https://blog.youkuaiyun.com/weixin_39436195/article/details/76101159

版权

leetcode database 专栏收录该内容

20 篇文章

订阅专栏

本文介绍了一种使用SQL查询的方法，旨在从包含重复数字的数据表中找出只出现一次的最大数值。通过子查询结合聚合函数COUNT()和MAX()，有效地筛选出符合要求的数据。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Question

Table number contains many numbers in column num including duplicated ones.
Can you write a SQL query to find the biggest number, which only appears once.
+---+
|num|
+---+
| 8 |
| 8 |
| 3 |
| 3 |
| 1 |
| 4 |
| 5 |
| 6 | 
For the sample data above, your query should return the following result:
+---+
|num|
+---+
| 6 |
Note:
If there is no such number, just output null.

Quick Navigation

Solution
- Approach: Using subquery and MAX() function [Accepted]

Solution

Approach: Using subquery and `MAX()` function [Accepted]

Algorithm

Use subquery to select all the numbers appearing just one time.

SELECT
    num
FROM
    `number`
GROUP BY num
HAVING COUNT(num) = 1;

Then choose the biggest one using MAX().

SELECT
    MAX(num) AS num
FROM
    (SELECT
        num
    FROM
        number
    GROUP BY num
    HAVING COUNT(num) = 1) AS t
;