res.txt

-- Write a SQL query to find all duplicate emails in a table named Person.

-- +----+---------+
-- | Id | Email   |
-- +----+---------+
-- | 1  | a@b.com |
-- | 2  | c@d.com |
-- | 3  | a@b.com |
-- +----+---------+
-- For example, your query should return the following for the above table:

-- +---------+
-- | Email   |
-- +---------+
-- | a@b.com |
-- +---------+
-- Note: All emails are in lowercase.

# Write your MySQL query statement below
SELECT t.eml AS 'Email' FROM 
(SELECT count(Email) AS 'cnt', Email AS 'eml' FROM Person GROUP BY Email) as t 
WHERE t.cnt>1;