196. Delete Duplicate Emails LeetCode Solution | Easy Approach

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Delete Duplicate Emails

SQL Schema

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.

Return the result table in any order.

The query result format is in the following example.

Example 1:

Input: 
Person table:
+----+------------------+
| id | email            |
+----+------------------+
| 1  | [email protected] |
| 2  | [email protected]  |
| 3  | [email protected] |
+----+------------------+
Output: 
+----+------------------+
| id | email            |
+----+------------------+
| 1  | [email protected] |
| 2  | [email protected]  |
+----+------------------+
Explanation: [email protected] is repeated two times. We keep the row with the smallest Id = 1.

Delete Duplicate Emails Solutions

Time: O(n)
Space: O(n)

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