Delete Duplicate Email LeetCode Programming Solutions | LeetCode Problem Solutions in C++, Java, & Python [💯Correct]

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Hello Programmers/Coders, Today we are going to share solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python. At Each Problem with Successful submission with all Test Cases Passed, you will get a score or marks and LeetCode Coins. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.

In this post, you will find the solution for the Delete Duplicate Email in C++, Java & Python-LeetCode problems. We are providing the correct and tested solutions to coding problems present on LeetCode. If you are not able to solve any problem, then you can take help from our Blog/website.

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Link for the Problem – Delete Duplicate Email– LeetCode Problem

Template – LeetCode Problem

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.

The query result format is in the following example.

Example 1:

Input: 
Person table:
+----+------------------+
| id | email            |
+----+------------------+
| 1  | john@example.com |
| 2  | bob@example.com  |
| 3  | john@example.com |
+----+------------------+
Output: 
+----+------------------+
| id | email            |
+----+------------------+
| 1  | john@example.com |
| 2  | bob@example.com  |
+----+------------------+
Explanation: john@example.com is repeated two times. We keep the row with the smallest Id = 1.

Delete Duplicate Email– LeetCode Solutions

Delete Duplicate Email Solution in SQL:

First Problem solution.

delete from Person
where Id in (select r.Id from  
             (select Id, row_number() over(partition by Email 
                                          order by Id
                                         ) as rk
             from Person) r
            where r.rk > 1
            );

Second Problem solution.

DELETE b
FROM Person a, Person b
WHERE a.Email = b.Email
AND a.Id < b.Id;

Third Problem solution.

delete from Person
where Id not in
(select mid from (select min(Id) as mid from Person
group by Email)T )