196. Delete duplicate email addresses

Problem description ：

SQL framework

surface : Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| email       | varchar |
+-------------+---------+
id Is the primary key column of the table .
 Each row of the table contains an email . Email will not contain uppercase letters .

Write a SQL Delete statements Come on Delete All duplicate emails , Keep only one id The smallest and only email .

With In any order Return result table . （ Be careful ： Just write a delete statement , The remaining results will be queried automatically ）

The query result format is as follows .

Example ：

Example 1:

 Input : 
Person  surface :
+----+------------------+
| id | email            |
+----+------------------+
| 1  | [email protected] |
| 2  | [email protected]  |
| 3  | [email protected] |
+----+------------------+
 Output : 
+----+------------------+
| id | email            |
+----+------------------+
| 1  | [email protected] |
| 2  | [email protected]  |
+----+------------------+
 explain : [email protected] Repeat twice . We keep the smallest Id = 1.

Pass times 153,609     Submit the number 226,963

On sql, Take it to run ：

Create table statement ：

CREATE TABLE `person` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `email` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

DELETE 
FROM
	`person` 
WHERE
	id IN ( 
	SELECT * from ( SELECT max( id ) AS id FROM `person` GROUP BY email HAVING count( * ) > 1 ) as a
	) 
	
	
	SELECT * from person 

Running results ：

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