# 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

```java
```
