[LeetCode]-DataBase-Delete Duplicate Emails

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  | john@example.com |
| 2  | bob@example.com  |
| 3  | john@example.com |
+----+------------------+
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  | john@example.com |
| 2  | bob@example.com  |
+----+------------------+

需求：删除重复数据，保留ID最小的

DELETE t1 FROM persons t1 LEFT JOIN(
SELECT MIN(Id) Id,Email FROM Persons GROUP BY Email HAVING COUNT(Email)>1
)t2 ON t1.Email=t2.Email
WHERE t1.Id>t2.Id