sql notes: leetcode#182 duplicate emails

Problem

Write a SQL query to find all duplicate emails in a table named Person.

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+----+---------+
| Id | Email   |
+----+---------+
| 1  | [email protected] |
| 2  | [email protected] |
| 3  | [email protected] |
+----+---------+

For example, your query should return the following for the above table:

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+---------+
| Email   |
+---------+
| [email protected] |
+---------+

Analysis

Group by Email and output groups that appear more than once.

Solution

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SELECT Email FROM Person GROUP BY Email HAVING COUNT(*) > 1;

Link

182. Duplicate Emails
(中文版) SQL 笔记: Leetcode#182 Duplicate Emails