Delete Duplicate Emails LeetCode Solution

Problem – Delete Duplicate Emails LeetCode Solution

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.

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.

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 LeetCode Solution in Oracle

 delete from Person where id not in (select min(id) from person group by email);

Delete Duplicate Emails LeetCode Solution in MS SQL Server

delete from person 
    where id not in (
        select Min(id) 
            from person
            group by email
    )
	```

Delete Duplicate Emails LeetCode Solution in My SQL

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