0196. Delete Duplicate Emails

https://leetcode.com/problems/delete-duplicate-emails

Description

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.

Return the result table in any order.

The query result format is in the following example.

Example 1:

**Input:** 
Person table:
+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | [e-mail] |
| 2  | [e-mail]  |
| 3  | [e-mail] |
+----+------------------+
**Output:** 
+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | [e-mail] |
| 2  | [e-mail]  |
+----+------------------+
**Explanation:** [e-mail] is repeated two times. We keep the row with the smallest Id = 1.

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