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Java-based LeetCode algorithm problem solutions, regularly updated
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.