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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
+-------------+---------+ | 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
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.
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 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 )