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leetcode/problem/duplicate-emails.html

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+<p>Table: <code>Person</code></p>
+
+<pre>
++-------------+---------+
+| 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.
+</pre>
+
+<p>&nbsp;</p>
+
+<p>Write an SQL query to report all the duplicate emails.</p>
+
+<p>Return the result table in <strong>any order</strong>.</p>
+
+<p>The query result format is in the following example.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> 
+Person table:
++----+---------+
+| id | email   |
++----+---------+
+| 1  | a@b.com |
+| 2  | c@d.com |
+| 3  | a@b.com |
++----+---------+
+<strong>Output:</strong> 
++---------+
+| Email   |
++---------+
+| a@b.com |
++---------+
+<strong>Explanation:</strong> a@b.com is repeated two times.
+</pre>