【Leetcode】Customers Who Never Order

题目链接：https://leetcode.com/problems/customers-who-never-order/

题目：
Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.

Table: Customers.

+—-+——-+
| Id | Name |
+—-+——-+
| 1 | Joe |
| 2 | Henry |
| 3 | Sam |
| 4 | Max |
+—-+——-+
Table: Orders.

+—-+————+
| Id | CustomerId |
+—-+————+
| 1 | 3 |
| 2 | 1 |
+—-+————+
Using the above tables as example, return the following:

+———–+
| Customers |
+———–+
| Henry |
| Max |
+———–+

思路：
left或right join，选择customerid为空的就是没有进行过交易的。

算法：

select Name from Customers c left outer join Orders o on o.CustomerId=c.Id where o.CustomerId is null

【Leetcode】Customers Who Never Order相关推荐

【leetcode】86. Partition List
题目如下: Given a linked list and a value x, partition it such that all nodes less than x come before no ...
【leetcode】109. Convert Sorted List to Binary Search Tree
题目如下: Given a singly linked list where elements are sorted in ascending order, convert it to a heigh ...
【LeetCode】863. All Nodes Distance K in Binary Tree 解题报告（Python）
[LeetCode]863. All Nodes Distance K in Binary Tree 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http ...
【Leetcode】100. 相同的树
题目给定两个二叉树,编写一个函数来检验它们是否相同. 如果两个树在结构上相同,并且节点具有相同的值,则认为它们是相同的. 示例 1: 输入: 1 1/ \ / \2 3 2 3[1,2,3], [1 ...
【leetcode】85. Maximal Rectangle 0/1矩阵的最大全1子矩阵
1. 题目 Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing only 1 ...
【leetcode】486. Predict the Winner
题目如下: Given an array of scores that are non-negative integers. Player 1 picks one of the numbers fro ...
【leetcode】132. Palindrome Partitioning II
题目如下: 解题思路:本题是[leetcode]131. Palindrome Partitioning的升级版,要求的是求出最小cuts,如果用[leetcode]131. Palindrome P ...
【Leetcode】103. 二叉树的锯齿形层次遍历
题目给定一个二叉树,返回其节点值的锯齿形层次遍历.(即先从左往右,再从右往左进行下一层遍历,以此类推,层与层之间交替进行). 例如: 给定二叉树 [3,9,20,null,null,15,7], 3 ...
【Leetcode】79.单词搜索
题目给定一个二维网格和一个单词,找出该单词是否存在于网格中. 单词必须按照字母顺序,通过相邻的单元格内的字母构成,其中"相邻"单元格是那些水平相邻或垂直相邻的单元格.同一个单元格 ...

【Leetcode】Customers Who Never Order

【Leetcode】Customers Who Never Order相关推荐

最新文章

热门文章