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leetcode原文引用：
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 |
+----+------------------+
我的sql语句：
DELETE FROM Person
WHERE
id NOT IN (SELECT
id
FROM
(SELECT
MIN(id) AS id
FROM
Person
GROUP BY email) AS a);版权声明：本文为博主原创文章，未经博主允许不得转载。
leetcode数据库sql之Delete Duplicate Emails
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原文地址：http://blog.csdn.net/zkn_cs_dn_2013/article/details/47304413
