From e3ca6ab8d1f13487300361e12fc87499fdffdf14 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=B5=B5=E6=95=8F?= <3234934487@qq.com>
Date: Fri, 17 Mar 2023 12:54:25 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BD=9C=E4=B8=9A?=
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---
 ...55\347\273\204\344\275\234\344\270\232.md" | 103 ++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 "56 \350\265\265\346\225\217/20230316 \347\254\254\345\205\255\347\273\204\344\275\234\344\270\232.md"

diff --git "a/56 \350\265\265\346\225\217/20230316 \347\254\254\345\205\255\347\273\204\344\275\234\344\270\232.md" "b/56 \350\265\265\346\225\217/20230316 \347\254\254\345\205\255\347\273\204\344\275\234\344\270\232.md"
new file mode 100644
index 0000000..ab966a5
--- /dev/null
+++ "b/56 \350\265\265\346\225\217/20230316 \347\254\254\345\205\255\347\273\204\344\275\234\344\270\232.md"	
@@ -0,0 +1,103 @@
+```mysql
+-- 创建数据库
+create database tt57 charset utf8;
+use tt57;
+-- 创建表格
+create table `user`(
+user_id int primary key,
+user_name varchar(5),
+user_tel varchar(11),
+ordertime date
+);
+create table `order`(
+order_id int,
+uesr_id int,
+type varchar(10),
+food varchar(10),
+number int,
+price int,
+foreign key (uesr_id) references `user` (user_id)
+);
+-- 插入数据
+insert into `user` values
+(1,'张三','19865645691','2023-3-13'),
+(2,'李四','12345675691','2023-3-13'),
+(3,'王五','12895678901','2023-3-13'),
+(4,'老六','12345678691','2023-3-14'),
+(5,'小七','18945678031',null),
+(6,'老八','19345678561','2023-3-16'),
+(7,'朱九','15845679911',null);
+insert into `order` values 
+(1,1,'快餐','肯德基全家桶',1,50),
+(2,1,'快餐','可乐',4,20),
+(3,6,'饮料','柠檬水',2,16),
+(4,2,'米饭','鱼香肉丝盖饭',5,60),
+(5,2,'饮料','珍珠奶茶',3,22),
+(6,3,'粉面类','螺蛳粉',4,28),
+(7,4,'粉面类','凉拌面',1,10);
+-- 根据上表所给信息完成下列题目：
+-- 1.在用户表（user）新增一个性别字段user_sex，数据类型为char。
+ALTER TABLE `user` ADD user_sex CHAR;
+-- 2.由于顾客3退单，请把此订单删除。
+DELETE 
+FROM
+	`order` 
+WHERE
+	order_id = 3;
+-- 3.老八的电话号码换新了，请将他的号码更新为8888888888。
+UPDATE `user` 
+SET user_tel = 8888888888 
+WHERE
+	user_name = '老八';
+-- 4.查询order表里的最高金额和总金额。
+SELECT
+	max( price ) 最高金额,
+	sum( price ) 总金额 
+FROM
+	`order`;
+-- 5.查询每个顾客分别订购了几个类别。
+SELECT DISTINCT
+	type,
+	user_name 
+FROM
+	`user` a
+	LEFT JOIN `order` b ON a.user_id = b.uesr_id 
+WHERE
+	b.uesr_id IS NOT NULL 
+ORDER BY
+	type;
+-- 6.查询饮料的总金额
+SELECT
+	sum( price ) 
+FROM
+	`order` 
+WHERE
+	type = '饮料';
+-- 7.查询订单表（order）里的订单号，类别（type），食物（food）.
+select order_id,type,food from `order`;
+-- 8.查询没吃饭的人的所有信息
+SELECT
+	a.* 
+FROM
+	`user` a
+	LEFT JOIN `order` b ON a.user_id = b.uesr_id 
+WHERE
+	b.uesr_id IS NULL;
+-- 9.查询姓老的人的全部信息及订单信息
+SELECT
+	* 
+FROM
+	`user` a
+	LEFT JOIN `order` b ON a.user_id = b.uesr_id 
+WHERE
+	a.user_name LIKE '老%';
+-- 10.查询总金额大于20的订单里最大值的用户信息，使用降序排列
+SELECT
+	a.* 
+FROM
+	`user` a
+	RIGHT JOIN `order` b ON a.user_id = b.uesr_id 
+WHERE
+	b.price > 20 and price=(SELECT max(price) from `order`);
+```
+
-- 
Gitee