LeetCode - Delete Duplicate Emails
Discription：Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id.
删除重复的Email地址，保留Id最小的那个。
使用自身连接循环即可。
# Write your MySQL query statement below
delete p1 from Person p1, Person p2
where p1.Email=p2.Email and p1.Id>p2.Id;
LeetCode - Delete Duplicate Emails的更多相关文章
- [LeetCode] Delete Duplicate Emails 删除重复邮箱
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique ...
- LeetCode——Delete Duplicate Emails（巧用mysql临时表）
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique ...
- Leetcode 182. Duplicate Emails
Write a SQL query to find all duplicate emails in a table named Person. +----+---------+ | Id | Emai ...
- LeetCode Database: Delete Duplicate Emails
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique ...
- leetcode【sql】 Delete Duplicate Emails
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique ...
- LeetCode DB : Delete Duplicate Emails
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique ...
- leetcode 196. Delete Duplicate Emails 配合查询的delete
https://leetcode.com/problems/delete-duplicate-emails/description/ 题意要对原来的数据表进行删除,不删除不行,它每次只输出原来那个表. ...
- LeetCode 196. Delete Duplicate Emails (删除重复的电子邮箱)
题目标签: 题目给了我们一个 email 的表格,让我们删除重复的. 建立Person p1,Person p2,当email 相同时,而且 p1 id 要大于 p2 id 时候,删除这一行. Jav ...
- leetcode 196. Delete Duplicate Emails
# 慢,内连接delete p1 from Person p1, Person p2 where p1.Email=p2.Email and p1.Id>p2.Id delete from Pe ...
随机推荐
- catalina.home和catalina.base这两个属性的作用
catalina.home和catalina.base这两个属性仅在你需要安装多个Tomcat实例而不想安装多个软件备份的时候使用,这样能节省磁盘空间.以Tomcat6.0为例,其Tomcat目录结构 ...
- 可供前端工程师选择的精彩CSS框架
在这里你有一个很酷的框架,收集创建的CSS布局. 如果你不喜欢框架,宁愿使用自己的手写代码以促进自己的发展,请跳过本篇文章. 我想有一个建设性的意见,那就是有选择的使用其优点避开其缺点. 就个人而言, ...
- e677. 模糊化图像
This example demonstrates a 3x3 kernel that blurs an image. Kernel kernel = new Kernel(3, 3, new flo ...
- 嵌入式驱动开发之usb 无线网卡驱动---RT2870STA dm368
RT2870STA 368的无线网卡驱动! http://www.linuxidc.com/Linux/2014-02/96979.htm
- java反射详解 （转至 http://www.cnblogs.com/rollenholt/archive/2011/09/02/2163758.html）
本篇文章依旧采用小例子来说明,因为我始终觉的,案例驱动是最好的,要不然只看理论的话,看了也不懂,不过建议大家在看完文章之后,在回过头去看看理论,会有更好的理解. 下面开始正文. [案例1]通过一个对象 ...
- c语言的fopen
c语言fopen函数 fopen函数用来打开一个文件,其调用的一般形式为: 文件指针名=fopen(文件名,使用文件方式); 其中, “文件指针名”必须是被说明为FILE 类型的指针变量: “文件名” ...
- mac Virtualbox Ubuntu 设置共享目录
如果要用VirtualBox自带的共享文件夹功能,必须先安装Guest Additions.安装方法:置顶的菜单条->devices->Install Guest Additions.点击 ...
- [python每日一库]——hotshot
High performance logging profiler 官方文档:http://docs.python.org/2/library/hotshot.html#module-hotshot ...
- Office密码破解不求人！
你用Office吗?你会为你的Office文档加密吗?如果Office密码忘了求人吗?最后一个问题是不是让你很头大,求人办事不是要费钱就是要靠人情,不如自己拥有一款强大的密码破解工具,想要Office ...
- linux环境中查看主机型号(机器型号)
需求说明: 今天一同事让统计测试环境主机型号,在此记录下. 操作过程: 1.通过dmidecode工具查询,产品型号(机器型号) [root@redhat6 ~]# dmidecode | grep ...