Published Sep 01, 2019
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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 |
+---------+
The GROUP BY clause groups a set of rows into a set of summary rows by values of columns
or expressions. The GROUP BY clause returns one row for each group. In other words, it
reduces the number of rows in the result set.
SELECT Email FROM Person GROUP BY Email HAVING COUNT(Email) > 1;