# leetcode\_619

SQL架构 Table my\_numbers 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.

## Solutions

1. **straight forward**

```sql
# Write your MySQL query statement below

SELECT IFNULL((SELECT num
                FROM my_numbers
                GROUP BY num
                HAVING COUNT(*) = 1
                ORDER BY num DESC
                LIMIT 1), null) AS num
```