Welcome to Subscribe On Youtube
Question
Formatted question description: https://leetcode.ca/all/182.html
Write a SQL query to find all duplicate emails in a table named Person.
+----+---------+
| Id | Email |
+----+---------+
| 1 | a@b.com |
| 2 | c@d.com |
| 3 | a@b.com |
+----+---------+
For example, your query should return the following for the above table:
+---------+
| Email |
+---------+
| a@b.com |
+---------+
Note: All emails are in lowercase.
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;