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Java-based LeetCode algorithm problem solutions, regularly updated

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619\. Biggest Single Number

Easy

SQL Schema

Table: `MyNumbers`

    +-------------+------+ 
    | Column Name | Type | 
    +-------------+------+ 
    | num         | int  |
    +-------------+------+ 

There is no primary key for this table. It may contain duplicates.

Each row of this table contains an integer.

A **single number** is a number that appeared only once in the `MyNumbers` table.

Write an SQL query to report the largest **single number**. If there is no **single number**, report `null`.

The query result format is in the following example.

**Example 1:**

**Input:** MyNumbers table: 

    +-----+ 
    | num | 
    +-----+ 
    | 8   | 
    | 8   | 
    | 3   | 
    | 3   | 
    | 1   | 
    | 4   | 
    | 5   | 
    | 6   | 
    +-----+

**Output:** 

    +-----+ 
    | num | 
    +-----+ 
    | 6   | 
    +-----+

**Explanation:** The single numbers are 1, 4, 5, and 6. Since 6 is the largest single number, we return it.

**Example 2:**

**Input:** MyNumbers table: 

    +-----+ 
    | num | 
    +-----+ 
    | 8   | 
    | 8   | 
    | 7   | 
    | 7   | 
    | 3   | 
    | 3   | 
    | 3   | 
    +-----+

**Output:** 

    +------+ 
    | num  | 
    +------+ 
    | null | 
    +------+

**Explanation:** There are no single numbers in the input table so we return null.