196. 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  |

+----+------------------+

删除重复的地址，保留ID最小的

MySQL（714ms）：

DELETE FROM Person

WHERE Id NOT IN (

   SELECT * FROM(

      SELECT MIN(Id)

      FROM Person

      GROUP BY Email

   ) AS Mid

);

巴特西

196. Delete Duplicate Emails

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