Delete Duplicate Emails---easy

删除Person表中重复的Email，只留下id最小的Email

Person表，主键是Id

+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | john@example.com |
| 2  | bob@example.com  |
| 3  | john@example.com |
+----+------------------+

结果：

+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | john@example.com |
| 2  | bob@example.com  |
+----+------------------+

SQL语句：

delete a from Person as a,Person as b where a.id>b.id and a.Email=b.Email;