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Question
Formatted question description: https://leetcode.ca/all/182.html
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 report all the duplicate emails. Note that it's guaranteed that the email field is not NULL.
Return the result table in any order.
The query result format is in the following example.
Example 1:
Input: Person table: +----+---------+ | id | email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+ Output: +---------+ | Email | +---------+ | a@b.com | +---------+ Explanation: a@b.com is repeated two times.
Algorithm
Group by…Having Count(*)…
Code
SQL
SELECT Email FROM Person GROUP BY Email
HAVING COUNT(*) > 1;
--
SELECT DISTINCT p1.Email FROM Person p1
JOIN Person p2 ON p1.Email = p2.Email
WHERE p1.Id <> p2.Id;