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Formatted question description: https://leetcode.ca/all/619.html
619. Biggest Single Number
Level
Easy
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.
Solution
Use select max(num) to select the biggest number. To select the biggest number that only appears once, use having count(num) = 1 as a condition.
# Write your MySQL query statement below
select max(num) as num
from (select num from my_numbers
group by num
having count(num) = 1) as t;