0619. Biggest Single Number

https://leetcode.com/problems/biggest-single-number

Description

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.

ac