196. Delete Duplicate Emails（必看）

max，min函数with group by是针对每组的数据求最大最小值

Approach: Using DELETE and WHERE clause

Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id.

+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | [email protected] |
| 2  | [email protected]  |
| 3  | [email protected] |
+----+------------------+
Id is the primary key column for this table.

For example, after running your query, the above Person table should have the following rows:

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

---

DELETE p1 FROM Person p1,
    Person p2
WHERE
    p1.Email = p2.Email AND p1.Id > p2.Id

mysql能运行但leetcode通不过：

SELECT MIN(Id) as Id, Email
FROM Person
group BY Email;

select distinct id, email from person
where id not in
(select p1.id
 from Person p1, person p2 
where p1.id > p2.id 
 and p1.email = p2.email);