196-delete_duplicate_emails.sql

-- 196. Delete Duplicate Emails

-- Write a SQL query to delete all duplicate email entries in a table named Person, 
-- keeping only unique emails based on its smallest Id.

-- +----+------------------+
-- | Id | Email            |
-- +----+------------------+
-- | 1  | john@example.com |
-- | 2  | bob@example.com  |
-- | 3  | john@example.com |
-- +----+------------------+

-- Id is the primary key column for this table.
-- For example, after running your query, the above Person table should have the following rows:

-- +----+------------------+
-- | Id | Email            |
-- +----+------------------+
-- | 1  | john@example.com |
-- | 2  | bob@example.com  |
-- +----+------------------+

-- Note:
-- Your output is the whole Person table after executing your sql. Use delete statement.


DELETE p1 FROM Person p1
        INNER JOIN Person p2
WHERE p1.Id > p2.Id AND p1.Email = p2.Email;