Leetcode Duplicate Emails problem solution

In this Leetcode Duplicate Emails problem solution we need to write a SQL query to find all duplicate emails in a table named Person.

Problem solution in Oracle.

SELECT email
FROM person
GROUP BY email
HAVING COUNT(email) > 1

The > = 2 seems faster. I have no idea why, coudl be pure luck

SELECT email
FROM person
GROUP BY email
HAVING COUNT(email) >= 2

Problem solution in Mysql.

select Email from (select count(distinct Id) , Email
from Person
Group by Email
Having count(distinct ID)>1) a;

Problem solution in C++.

Select Email FROM Person 
Group by Email Having count(Email) > 1