readme.md

My solutions to Leetcode Database Problems

I will put my solutions to Leetcode Database Problems in this repo.

Please feel free to contact me if you have any questions with this repo:)

email: liuyubobobo@gmail.com

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大家好，欢迎大家来到我的 Leetcode 数据库题解代码仓。在这个代码仓中。如果对代码仓有任何问题，欢迎联系我：）

电子邮件：liuyubobobo@gmail.com

知乎: 刘宇波 http://www.zhihu.com/people/liuyubobobo

知乎专栏：是不是很酷 https://zhuanlan.zhihu.com/liuyubobobo

个人公众号：是不是很酷：）

知识星球（免费）

其他相关代码仓

• 《算法与数据结构》课程, 代码仓: Play-with-Algorithms

• 《玩转算法面试》课程, 代码仓: Play-with-Algorithm-Interview

• 《看得见的算法》课程, 代码仓: Play-with-Algorithm-Visualization

• 《玩转数据结构》课程, 代码仓: Play-with-Data-Structures

• 《玩转图论算法》课程, 代码仓: Play-with-Graph-Algorithms

• Leetcode 算法题解代码仓：Play Leetcode （注：以C++实现为主）

Problems

ID	Problem	Official Solution	MySQL	Comments
175	Combine Two Tables	solution	MySQL
176	Second Highest Salary	solution	MySQL
181	Employees Earning More Than Their Managers	solution	MySQL
182	Duplicate Emails	solution	MySQL
183	Customers Who Never Order	solution	MySQL
184	Department Highest Salary	solution	MySQL
196	Delete Duplicate Emails	solution	MySQL	DELETE FROM SELF JOIN Table
197	Rising Temperature	solution	MySQL	DATE_SUB or DATEDIFF
511	Game Play Analysis I	[无]	MySQL
570	Managers with at Least 5 Direct Reports	solution	MySQL
580	Count Student Number in Departments	solution	MySQL
584	Find Customer Referee	solution	MySQL	IFNULL
586	Customer Placing the Largest Number of Orders	solution	MySQL	ORDER BY and LIMIT 1 to get max/min value
595	Big Countries	solution	MySQL
607	Sales Person	solution	MySQL
608	Tree Node	solution	MySQL	IF or CASE
619	Biggest Single Number	solution	MySQL
627	Swap Salary	solution	MySQL	IF or CASE
1050	Actors and Directors Who Cooperated At Least Three Times	[无]	MySQL
1084	Sales Analysis III	[无]	MySQL
1112	Highest Grade For Each Student	[无]	MySQL
1141	User Activity for the Past 30 Days I	[无]	MySQL
1148	Article Views I	[无]	MySQL
1158	Market Analysis I	[无]	MySQL	The diff between WHERE and AND in LEFT JOIN
1173	Immediate Food Delivery I	[无]	MySQL
1211	Queries Quality and Percentage	[无]	MySQL
1251	Average Selling Price	[无]	MySQL
1264	Page Recommendations	[无]	MySQL
1280	Students and Examinations	[无]	MySQL
1303	Find the Team Size	[无]	MySQL
1350	Students With Invalid Departments	[无]	MySQL
1393	Capital Gain/Loss	[无]	MySQL
1398	Customers Who Bought Products A and B but Not C	[无]	MySQL
1407	Top Travellers	[无]	MySQL
1440	Evaluate Boolean Expression	[无]	MySQL	JOIN 3 Tables
1445	Apples & Oranges	[无]	MySQL
1484	Group Sold Products By The Date	[无]	MySQL	GROUP_CONCAT
1527	Patients With a Condition	[无]	MySQL
1571	Warehouse Manager	[无]	MySQL
1581	Customer Who Visited but Did Not Make Any Transactions	[无]	MySQL
1587	Bank Account Summary II	[无]	MySQL	JOIN (NOT LEFT JOIN)
1607	Sellers With No Sales	[无]	MySQL
1633	Percentage of Users Attended a Contest	[无]	MySQL
1667	Fix Names in a Table	[无]	MySQL	UPPER, LOWER, SUBSTRING, CONCAT
1693	Daily Leads and Partners	[无]	MySQL
1699	Number of Calls Between Two Persons	[无]	MySQL	GREATEST, LEAST
1729	Find Followers Count	[无]	MySQL
1741	Find Total Time Spent by Each Employee	[无]	MySQL
1757	Recyclable and Low Fat Products	[无]	MySQL
1795	Rearrange Products Table	[无]	MySQL
1873	Calculate Special Bonus	[无]	MySQL	SELECT CASE 或者 SELECT IF 的使用
1890	The Latest Login in 2020	[无]	MySQL	YEAR
1965	Employees With Missing Information	[无]	MySQL