leetcode586. 订单最多的客户（必会)-CFANZ编程社区

问题描述：

在表 orders 中找到订单数最多客户对应的 customer_number 。

数据保证订单数最多的顾客恰好只有一位。

表 orders 定义如下：

| Column            | Type      |
|-------------------|-----------|
| order_number (PK) | int       |
| customer_number   | int       |
| order_date        | date      |
| required_date     | date      |
| shipped_date      | date      |
| status            | char(15) |
| comment           | char(200) |
样例输入

| order_number | customer_number | order_date | required_date | shipped_date | status | comment |
|--------------|-----------------|------------|---------------|--------------|--------|---------|
| 1            | 1               | 2017-04-09 | 2017-04-13    | 2017-04-12   | Closed |         |
| 2            | 2               | 2017-04-15 | 2017-04-20    | 2017-04-18   | Closed |         |
| 3            | 3               | 2017-04-16 | 2017-04-25    | 2017-04-20   | Closed |         |
| 4            | 3               | 2017-04-18 | 2017-04-28    | 2017-04-25   | Closed |         |
样例输出

| customer_number |
|-----------------|
| 3 |

sql语句，拿去即可运行：

DDL语句：

/*
 Navicat Premium Data Transfer

 Source Server         : 我的mysql
 Source Server Type    : MySQL
 Source Server Version : 50736
 Source Host           : 8.136.255.28:3306
 Source Schema         : test

 Target Server Type    : MySQL
 Target Server Version : 50736
 File Encoding         : 65001

 Date: 12/01/2022 10:42:11
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for orders
-- ----------------------------
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders`  (
  `order_number` int(10) NOT NULL AUTO_INCREMENT,
  `customer_number` int(10) DEFAULT NULL,
  `order_date` datetime(0) DEFAULT NULL,
  `required_date` datetime(0) DEFAULT NULL,
  `shipped_date` datetime(0) DEFAULT NULL,
  `status` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
  `comment` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
  PRIMARY KEY (`order_number`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of orders
-- ----------------------------
INSERT INTO `orders` VALUES (1, 1, '2022-01-12 10:33:35', '2022-01-12 10:33:46', '2022-01-12 10:34:01', '0', '0');
INSERT INTO `orders` VALUES (2, 2, '2022-01-12 10:33:38', '2022-01-12 10:33:48', '2022-01-12 10:34:04', '1', '0');
INSERT INTO `orders` VALUES (3, 3, '2022-01-12 10:33:41', '2022-01-12 10:33:51', '2022-01-12 10:34:09', '0', '0');
INSERT INTO `orders` VALUES (4, 3, '2022-01-12 10:33:44', '2022-01-12 10:33:54', '2022-01-12 10:34:12', '0', '0');

SET FOREIGN_KEY_CHECKS = 1;

select customer_number
from orders
group by customer_number
order by count(*) desc limit 1;

运行结果：

大佬的自动忽略，需要的cv运行一下，感受会不一样

我要刷100道算法题，第91道