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+# 笔记
+
+多注意表与表之间的关系
+
+# 作业
+
+<a href="https://sm.ms/image/rfogCDWbZzHksUi" target="_blank"><img src="https://s2.loli.net/2023/09/17/rfogCDWbZzHksUi.png" ></a>
+
+```mysql
+/*==============================================================*/
+/* DBMS name:      MySQL 5.0                                    */
+/* Created on:     2023/9/17 18:11:14                           */
+/*==============================================================*/
+create database qiche charset utf8;
+use qiche;
+
+drop table if exists automobile;
+
+drop table if exists client;
+
+drop table if exists record;
+
+drop table if exists salesman;
+
+/*==============================================================*/
+/* Table: automobile                                            */
+/*==============================================================*/
+create table automobile #汽车
+(
+   a_id                 int(3) not null auto_increment,  #汽车编号
+   a_name               varchar(10) not null,            #汽车名称
+   a_sellingprice       decimal(7,1) not null,           #汽车售价
+   a_brand              varchar(10) not null,            #汽车品牌
+   primary key (a_id)
+);
+insert into automobile values 
+(01,'五菱神光mini',20000.0,'五菱宏光'),
+(02,'玛拉莎蒂2023',900000.0,'玛莎拉蒂'),
+(03,'宝牛SUV',250000.0,'宝马'),
+(04,'五菱宏光2077',10000.0,'五菱宏光');
+
+/*==============================================================*/
+/* Table: client                                                */
+/*==============================================================*/
+create table client #顾客
+(
+   c_id                 int(2) not null auto_increment, #顾客编号
+   c_name               varchar(10) not null,           #顾客姓名
+   c_sex                varchar(2) not null,            #顾客性别
+   primary key (c_id)
+);
+insert into client values 
+(2001,'德莱厄斯','男'),
+(2002,'塞恩','男'),
+(2003,'蒙多','男');
+/*==============================================================*/
+/* Table: record                                                */
+/*==============================================================*/
+
+
+/*==============================================================*/
+/* Table: salesman                                              */
+/*==============================================================*/
+create table salesman #销售员
+(
+   s_id                 int(2) not null auto_increment, #工号
+   s_name               varchar(5) not null,            #姓名
+   s_sex                varchar(2) not null,            #性别
+   primary key (s_id)
+);
+insert into salesman values 
+(1001,'梦泪','男'),
+(1002,'坤哥','男'),
+(1003,'厄斐琉斯','男');
+
+create table record #销售记录
+(
+   r_id                 int(2) not null auto_increment, #销售编号
+   s_id                 int not null,                   #工号
+   c_id                 int not null,                   #顾客编号
+   a_id                 int not null,                   #汽车编号
+   primary key (r_id)
+);
+insert into record values
+(3001,1001,2002,02),
+(3002,1002,2001,01),
+(3003,1001,2002,03),
+(3004,1003,2003,04);
+
+alter table record add constraint FK_Relationship_2 foreign key (s_id)
+      references salesman (s_id) on delete restrict on update restrict;
+
+alter table record add constraint FK_Relationship_3 foreign key (c_id)
+      references client (c_id) on delete restrict on update restrict;
+
+alter table record add constraint FK_Relationship_4 foreign key (a_id)
+      references automobile (a_id) on delete restrict on update restrict;
+  -- 1.查询特定销售员的销售记录
+SELECT
+	s.s_id 工号,
+	s_name 销售员,
+	r_id 销售编号,
+	a_name 汽车型号,
+	a_sellingprice 售价,
+	a_brand 汽车品牌 
+FROM
+	salesman s
+	JOIN record r
+	JOIN automobile a ON s.s_id = r.s_id 
+	AND a.a_id = r.a_id 
+WHERE
+	s.s_id =(
+	SELECT
+		s_id 
+	FROM
+		salesman 
+	WHERE
+		s_name = '梦泪' 
+	);
+	-- 2.查找销售记录中销售价格最高的汽车
+	select a.* from record r join automobile a on r.a_id=a.a_id where r.a_id = (select a_id from automobile where a_brand=(select max(a_brand) from automobile));
+	-- 3.统计某个销售员的销售总额
+SELECT
+	s_name 销售员,
+	sum(a_sellingprice) 销售总额
+FROM
+	salesman s
+	JOIN record r
+	JOIN automobile a ON s.s_id = r.s_id 
+	AND a.a_id = r.a_id
+	group by s.s_name having s.s_name='梦泪';
+	-- 4.根据客户信息查询其购买过的汽车
+	select c_name 顾客,c_sex 性别,a_name 汽车型号, a_sellingprice 售价,a_brand 型号 from client c join record r join automobile a on c.c_id=r.c_id and r.a_id = a.a_id where c.c_name='塞恩';
+	-- 5.分析特定品牌汽车的销售情况，统计每个品牌的销售数量和总销售额
+SELECT
+	a_brand 品牌,
+	count( r.a_id) 销售数量,
+	sum( a.a_sellingprice ) 销售总额 
+FROM
+	record r
+	JOIN automobile a ON r.a_id = a.a_id 
+GROUP BY
+	a_brand;
+	-- 6.检索特定日期范围内的销售了哪些汽车
+	-- 7.查找某车型的销售历史。
+	SELECT
+	a_name 汽车型号,
+	a_brand 品牌,
+	r.a_id 销售数量,
+	a.a_sellingprice  销售总额 
+FROM
+	record r
+	JOIN automobile a ON r.a_id = a.a_id where a.a_name='五菱神光mini';
+	-- 8.统计每个销售员的销售数量
+SELECT
+	s_name 销售员,
+	count(r.a_id) 销售总额
+FROM
+	salesman s
+	JOIN record r
+	JOIN automobile a ON s.s_id = r.s_id 
+	AND a.a_id = r.a_id
+	group by s.s_name;
+```
+