本题以删除重复邮箱为例,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。
Person:
| Id | |
|---|---|
| 1 | [email protected] |
| 2 | [email protected] |
| 3 | [email protected] |
答:
DELETE
p1
FROM
Person p1,
Person p2
WHERE
p1.Email = p2.Email AND p1.Id > p2.Id;
结果:
| Id | |
|---|---|
| 1 | [email protected] |
| 2 | [email protected] |