leetcode 182.duplicate emails

问题描述：

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

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

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

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

问题求解：

按Email分组查询并筛选出记录数目大于1的分组，选择其Email字段：

1
2
3

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

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