Delete Duplicate Emails

Problem

Table: Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| email       | varchar |
+-------------+---------+
id is the primary key column for this table.
Each row of this table contains an email. The emails will not contain uppercase letters.

Write an SQL query to delete all the duplicate emails, keeping only one unique email with the smallest id. Note that you are supposed to write a DELETE statement and not a SELECT one.

After running your script, the answer shown is the Person table. The driver will first compile and run your piece of code and then show the Person table. The final order of the Person table does not matter.

Solution

The problem Delete Duplicate Emails can be solved by using Multi-Table Deletes from MySQL.

Implementation

# Please write a DELETE statement and DO NOT write a SELECT statement.
# Write your MySQL query statement below

DELETE p2
FROM
  person AS p1,
  person AS p2
WHERE p1.email = p2.email AND p1.id < p2.id;