难度:Easy
编写一个 SQL 查询,来删除 Person 表中所有重复的电子邮箱,重复的邮箱里只保留 Id 最小 的那个。
+----+------------------+| Id | Email |+----+------------------+| 1 | [email protected] || 2 | [email protected] || 3 | [email protected] |+----+------------------+Id 是这个表的主键。例如,在运行你的查询语句之后,上面的 Person 表应返回以下几行:+----+------------------+| Id | Email |+----+------------------+| 1 | [email protected] || 2 | [email protected] |+----+------------------+
条件语句:
DELETE p1 from Person p1, Person p2 WHERE p1.Email =p2.Email AND p1.Id>p2.Id