LEETCODE数据库:196.DeleteDuplicateEmails

发表于 更新于 分类于 Waline： 阅读次数：

题目

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

Note:

Your output is the whole Person table after executing your sql. Use delete statement.

题解

1
2
3
DELETE p1
FROM Person p1,Person p2
WHERE p1.Email=p2.Email AND p1.Id>p2.Id;