一.题目 175. Combine Two Tables 二.分析 连接查询的时候要考虑where和on的区别 where : 查询时,连接的时候是必须严格满足条件的,满足了才会加入到临时表中. on : 查询时,考虑要满足这个条件,如果不满足则不会添加连接的表中的数据. 三.AC代码 SELECT FirstName, LastName, City, State FROM Person p LEFT JOIN Address a ON p.PersonID = a.PersonID;…

https://leetcode.com/problems/combine-two-tables/ Combine Two Tables Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

给定两个表,一个是人,一个是地址,要求查询所有人,可以没有地址. select a.FirstName, a.LastName, b.City, b.State from Person as a left join Address as b Using(PersonId); 详细可参考:https://www.cnblogs.com/grandyang/p/5348900.html…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

https://leetcode.com/problemset/database/ ACM退役,刚好要学sql,一定要刷题才行,leetcode吧. 这一题,说了两个表,一个左一个右吧,左边的personId是唯一的,但是右边的PersonId是不唯一的,所以不去重. 然后,总结下各种join的用法. 1.inner join,On XXX,需要左边有,右边也有,就输出该行. 2.outer join / 有些书叫 full join,左边有,右边没,也输出,右边没的就用NULL代替.同理右边有…

题目标签: 题目给了我们两个table,让我们合并,根据Person为主. 因为题目说了 提供person 信息,不管这个人有没有地址.所以这里用Left Join. Java Solution: Runtime:  244 ms, faster than 40 % 完成日期:05/22/2019 关键点:Left Join # Write your MySQL query statement below Select FirstName, LastName, City, State From…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

leetcode竟然有sql的题了..两道简单的应该会做 这个题主要就是一个left join... # Write your MySQL query statement below SELECT Person.FirstName, Person.LastName, Address.City, Address.State FROM Person LEFT JOIN Address ON Person.PersonId = Address.PersonId;…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

因为对数据库的内容早都忘得差不多了,所以我的第一感觉是: select Person.FirstName, Person.LastName, Address.City from Person, Address where Person.PersonId=Address.PersonId 结果出错了: 因为至少这个人是存在的,只是没有她的地址,你不至于搜不到吧, 但是我这种写法是引用两个表,从两个表中获取数据,就是找两者相同的情况下的结果. 使用join 可以连接两个表: join: 如果表中有一…

Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the primary key column for this table. Table: Address +--…

终于将LeetCode的免费题刷完了,真是漫长的第一遍啊,估计很多题都忘的差不多了,这次开个题目汇总贴,并附上每道题目的解题连接,方便之后查阅吧~ 477 Total Hamming Distance 44.10% Meidum 475 Heaters  30.20% Easy 474 Ones and Zeroes  34.90% Meidum 473 Matchsticks to Square  31.80% Medium 472 Concatenated Words 29.20% Hard…

LeetCode有10道SQL的题目,最近学习SQL语言,顺便刷题强化一下, 说实话刷完SQL学习指南这本书,不是很难,上面的例子 跟语法规则我都能理解透, 实际中来做一些比较难的业务逻辑题,却一下子很难想起如何利用SQL来描述 还是要多刷题开阔自己的思路,把学到手的语法加以练习 应用到实际中去 197. Rising Temperature Given a Weather table, write a SQL query to find all dates' Ids with higher t…

175. Combine Two Tables 使用外连接即可. # Write your MySQL query statement below select FirstName, LastName, City, State from Person left outer join Address on Person.PersonId = Address.PersonId; # Write your MySQL query statement below select p.FirstName,…

175 Combine Two Tables 题目:左连接Person表和Address表. select FirstName,LastName,City,State from Person p left join Address a on p.PersonId=a.PersonId; 7个case耗时1001ms(注意耗时多次提交会不同,一般相差不大,偶尔也有相差大的)   --2015/1/11 176 Second Highest Salary 题目:写一条sql语句查询Employee …

leetcode 主要是一个针对北美的coder人群找工作的代码练习网站,我在2015年初次接触这个网站的时候,总共只有200多道题目,是一个类似acm 的a题网站.这些年变化越来越大,主要是因为找工作当然是多样化的考核过程,leetcode 也逐渐与时俱进,推出了下面几个类别的联系,今天我们随便挑几个练习一下: 175. Combine Two Tables -SQL Table: Person Column Name Type PersonId int FirstName varchar L…

题目从难到易记录.解题过程中,如果不太熟悉,可以将题目中的表自己手动录入到自己的数据库中,就方便学习,测试. 185. Department Top Three Salaries 要求就是查询出每个部门工资在前三的人.题意值得注意的一点就是,要求找出的是工资数前三的人,而不是工资最高的前三位.区别就是前者查询出来的人可能大于3,而后者最大只能为3. 最终答案: select b.Name Department,a.Name Employee,a.Salary from (select Name,…

All LeetCode Questions List(Part of Answers, still updating) 题目汇总及部分答案(持续更新中) Leetcode problems classified by company 题目按公司分类(Last updated: October 2, 2017) .   Top Interview Questions # Title Difficulty Acceptance 1 Two Sum Medium 17.70% 2 Add Two N…

终于将LeetCode的免费题刷完了,真是漫长的第一遍啊,估计很多题都忘的差不多了,这次开个题目汇总贴,并附上每道题目的解题连接,方便之后查阅吧~ 如果各位看官们,大神们发现了任何错误,或是代码无法通过OJ,或是有更好的解法,或是有任何疑问,意见和建议的话,请一定要在对应的帖子下面评论区留言告知博主啊(如果不方便注册博客园的话,可以下载下文提到的APP,在Feedback中给博主发邮件交流哈),同时也请大家踊跃地,大量地,盲目地提供各个题目的follow up一起讨论哈,多谢多谢,祝大家刷得愉快…

175. Combine Two Tables https://leetcode.com/problems/combine-two-tables/description/ Description Person 表: Column Name Type PersonId int FirstName varchar LastName varchar Address 表: Column Name Type AddressId int PersonId int City varchar State var…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 公众号:负雪明烛 本文关键词:刷题顺序,刷题路径,好题,top100,怎么刷题,Leetcode, 力扣,Python, C++, Java 大家好,相信很多朋友在刷题时,看到 LeetCode 的 2000 多道题目,有点手足无措,非常需要一个刷题的顺序和清单. 我整理了在 LeetCode(中文版)上点赞数前 100 的题目,这些的题目基本都在千赞以上,全部都是好题. 举个例子,1…

[175]Combine Two Tables (2018年11月23日,开始集中review基础) Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | PersonId | int | | FirstName | varchar | | LastName | varchar | +-------------+---------+ PersonId is the pr…

原文链接:http://www.c-sharpcorner.com/UploadFile/3d39b4/relationship-in-entity-framework-using-code-first-approach-w/ In this article, you will learn about relationships in Entity Framework using the Code First Approach with Fluent API. 在这篇文章中,你将会学习到使用EF…

The Employee table holds all employees. Every employee has an Id, and there is also a column for the department Id. +----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000…