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+# 作业
+
+## 1.
+
+```mysql
+-- 1、创建数据库test01_market
+create database test01_market;
+-- 2、创建表格customers
+use test01_market;
+-- | 字段名    | 数据类型    |
+-- | --------- | ----------- |
+-- | c_num     | int（11）   |
+-- | c_name    | varchar(50) |
+-- | c_contact | varchar(50) |
+-- | c_city    | varchar(50) |
+-- | c_birth   | date        |
+create table customers(
+c_num int,
+c_name varchar(50),
+c_contact varchar(50),
+c_city varchar(50),
+c_birth date
+);
+-- **要求3：**将c_contact字段移动到c_birth字段后面
+alter table customers change c_contact c_city1 varchar(50);
+alter table customers change c_city c_contact varchar(50);
+alter table customers change c_city1 c_city varchar(50);
+-- **要求4：**将c_name字段数据类型改为 varchar(70)
+alter table customers modify c_name varchar(70);
+-- **要求5：**将c_contact字段改名为c_phone
+alter table customers change c_contact c_phone varchar(50);
+-- **要求6：**增加c_gender字段到c_name后面，数据类型为char(1)
+alter table customers add c_gender char(1) after c_name;
+-- **要求7：**将表名改为customers_info
+alter table customers rename customers_into;
+-- **要求8：**删除字段c_city
+alter table customers drop c_city;
+```
+
+## 2.
+
+```mysql
+-- 1、创建数据库test02_library
+create database test02_library;
+-- 2、创建表格books
+-- | 字段名  | 字段说明 | 数据类型      | 允许为空 | 唯一 |
+-- | ------- | -------- | ------------- | -------- | ---- |
+-- | b_id    | 书编号   | int(11)       | 否       | 是   |
+-- | b_name  | 书名     | varchar（50） | 否       | 否   |
+-- | authors | 作者     | varchar(100)  | 否       | 否   |
+-- | price   | 价格     | float         | 否       | 否   |
+-- | pubdate | 出版日期 | year          | 否       | 否   |
+-- | note    | 说明     | varchar(100)  | 是       | 否   |
+-- | num     | 库存     | int(11)       | 否       | 否   |
+use test02_library;
+create table books(
+b_id int,
+b_name varchar(50),
+`authors` varchar(100),
+price float,
+pubdate year,
+note varchar(100),
+num int
+);
+desc books;
+select * from books;
+-- 3、向books表中插入记录
+-- 1） 指定所有字段名称插入第一条记录
+insert into books(b_id,b_name,`authors`,price,pubdate,note,num) values (1,'Tal of AAA','Dickes',23,1995,'novel',11);
+-- 2）不指定字段名称插入第二记录
+insert into books values (2,'EmmaT','Jane lura',35,1993,'joke',22);
+-- 3）同时插入多条记录（剩下的所有记录）
+insert into books(b_id,b_name,`authors`,price,pubdate,note,num) values (3,'Story of Jane','Jane Tim',40,2001,'novel',0),(4,'Lovey Day','George Byron',20,2005,'novel',30),(5,'Old land','Honore Blade',30,2010,'law',0),(6,'The Battle','Upton Sara',30,1999,'medicine',40),(7,'Rose Hood','Richard haggard',28,2008,'cartoon',28);
+-- | b_id | b_name        | authors         | price | pubdate | note     | num  |
+-- | ---- | ------------- | --------------- | ----- | ------- | -------- | ---- |
+-- | 1    | Tal of AAA    | Dickes          | 23    | 1995    | novel    | 11   |
+-- | 2    | EmmaT         | Jane lura       | 35    | 1993    | joke     | 22   |
+-- | 3    | Story of Jane | Jane Tim        | 40    | 2001    | novel    | 0    |
+-- | 4    | Lovey Day     | George Byron    | 20    | 2005    | novel    | 30   |
+-- | 5    | Old land      | Honore Blade    | 30    | 2010    | law      | 0    |
+-- | 6    | The Battle    | Upton Sara      | 30    | 1999    | medicine | 40   |
+-- | 7    | Rose Hood     | Richard haggard | 28    | 2008    | cartoon  | 28   |
+-- 
+-- 4、将小说类型(novel)的书的价格都增加5。
+update books set price = price + 5 where note = 'novel';
+-- 5、将名称为EmmaT的书的价格改为40。
+update books set price = 40 where b_name = 'EmmaT';
+-- 6、删除库存为0的记录
+delete from books where num = 0;
+```
+
+## 3.
+
+```
+-- 1、创建数据库test03_bookstore
+create database test03_bookstore;
+-- 2、创建book表
+use test03_bookstore;
+-- ```mysql
+-- +----------+--------------+------+-----+---------+----------------+
+-- | Field    | Type         | Null | Key | Default | Extra          |
+-- +----------+--------------+------+-----+---------+----------------+
+-- | id       | int(11)      | NO   | PRI | NULL    | auto_increment |
+-- | title    | varchar(100) | NO   |     | NULL    |                |
+-- | author   | varchar(100) | NO   |     | NULL    |                |
+-- | price    | double(11,2) | NO   |     | NULL    |                |
+-- | sales    | int(11)      | NO   |     | NULL    |                |
+-- | stock    | int(11)      | NO   |     | NULL    |                |
+-- | img_path | varchar(100) | NO   |     | NULL    |                |
+-- +----------+--------------+------+-----+---------+----------------+
+CREATE TABLE book(
+id int(11) NULL UNIQUE COMMENT 'auto_increment',
+title varchar(100) NOT NULL,
+author varchar(100) NOT NULL,
+price double(11,2) NOT NULL,
+sales int(11) NOT NULL,
+stock int(11) NOT NULL,
+img_path varchar(100) NOT NULL
+);
+DESC book;
+SELECT *FROM book;
+-- 尝试添加部分模拟数据，参考示例如下：
+-- 
+-- ```mysql
+-- +----+-------------+------------+-------+-------+-------+----------------------------+
+-- | id | title       | author     | price | sales | stock | img_path                   |
+-- +----+-------------+------------+-------+-------+-------+-----------------------------+
+-- |  1 | 解忧杂货店    | 东野圭吾   | 27.20 |   102 |    98 | upload/books/解忧杂货店.jpg   |
+-- |  2 | 边城         | 沈从文     | 23.00 |   102 |    98 | upload/books/边城.jpg       |
+-- +----+---------------+------------+-------+-------+-------+----------------------------+
+INSERT INTO book VALUES(1,'解忧杂货店','东野圭吾',27.20,102,98,'upload/books/解忧杂货店.jpg'),
+(2,'边城','沈从文',23.00,102,98,'upload/books/边城.jpg');
+-- 3、创建用户表users，并插入数据
+-- 
+-- ```mysql
+-- +----------+--------------+------+-----+---------+----------------+
+-- | Field    | Type         | Null | Key | Default | Extra          |
+-- +----------+--------------+------+-----+---------+----------------+
+-- | id       | int(11)      | NO   | PRI | NULL    | auto_increment |
+-- | username | varchar(100) | NO   | UNI | NULL    |                |
+-- | password | varchar(100) | NO   |     | NULL    |                |
+-- | email    | varchar(100) | YES  |     | NULL    |                |
+-- +----------+--------------+------+-----+---------+----------------+
+CREATE TABLE users(
+id int(11) NOT NULL UNIQUE COMMENT 'auto_increment',
+username varchar(100) NOT NULL UNIQUE,
+password varchar(100) NOT NULL,
+email varchar(100) NULL
+);
+-- 尝试添加部分模拟数据，参考示例如下：
+
+-- ```mysql
+-- +----+----------+----------------------------------+--------------------+
+-- | id | username | password                         | email              |
+-- +----+----------+----------------------------------+--------------------+
+-- |  1 | admin    | 112233                           | admin@mxdx.com     |
+-- +----+----------+----------------------------------+--------------------+
+INSERT INTO users VALUES(1,'admin',112233,'admin@mxdx.com');
+DESC users;
+SELECT *FROM users;
+-- 4、创建订单表orders
+-- 
+-- ```mysql
+-- +--------------+--------------+------+-----+---------+-------+
+-- | Field        | Type         | Null | Key | Default | Extra |
+-- +--------------+--------------+------+-----+---------+-------+
+-- | id           | varchar(100) | NO   | PRI | NULL    |       |
+-- | order_time   | datetime     | NO   |     | NULL    |       |
+-- | total_count  | int(11)      | NO   |     | NULL    |       |
+-- | total_amount | double(11,2) | NO   |     | NULL    |       |
+-- | state        | int(11)      | NO   |     | NULL    |       |
+-- | user_id      | int(11)      | NO   | MUL | NULL    |       |
+-- +--------------+--------------+------+-----+---------+-------+
+id varchar(100) NOT NULL UNIQUE,
+order_time datetime NOT NULL,
+total_count int(11) NOT NULL,
+total_amount double(11,2) NOT NULL,
+state int(11) NOT NULL,
+user_id int(11) NOT NULL UNIQUE
+);
+-- 尝试添加部分模拟数据，参考示例如下：
+-- 
+-- ```mysql
+-- +----------------+---------------------+-------------+--------------+-------+---------+
+-- | id             | order_time          | total_count | total_amount | state | user_id |
+-- +----------------+---------------------+-------------+--------------+-------+---------+
+-- | 15294258455691 | 2018-06-20 00:30:45 |           2 |        50.20 |     0 |       1 |
+-- +----------------+---------------------+-------------+--------------+-------+---------+
+INSERT INTO orders VALUES(15294258455691,'2018-06-20 00:30:45',2,50.20,0,1);
+-- 5、创建订单明细表order_items
+CREATE TABLE order_items(
+id int(11) NOT NULL UNIQUE COMMENT 'auto_increment',
+count int(11) NOT NULL,
+amount double(11,2) NOT NULL,
+title varchar(100) NOT NULL,
+author varchar(100) NOT NULL,
+price double(11,2) NOT NULL,
+img_path varchar(100) NOT NULL,
+order_id varchar(100) UNIQUE NOT NULL
+);
+-- ```mysql
+-- +----------+--------------+------+-----+---------+----------------+
+-- | Field    | Type         | Null | Key | Default | Extra          |
+-- +----------+--------------+------+-----+---------+----------------+
+-- | id       | int(11)      | NO   | PRI | NULL    | auto_increment |
+-- | count    | int(11)      | NO   |     | NULL    |                |
+-- | amount   | double(11,2) | NO   |     | NULL    |                |
+-- | title    | varchar(100) | NO   |     | NULL    |                |
+-- | author   | varchar(100) | NO   |     | NULL    |                |
+-- | price    | double(11,2) | NO   |     | NULL    |                |
+-- | img_path | varchar(100) | NO   |     | NULL    |                |
+-- | order_id | varchar(100) | NO   | MUL | NULL    |                |
+-- +----------+--------------+------+-----+---------+----------------+
+
+-- 尝试添加部分模拟数据，参考示例如下：
+-- 
+-- ```mysql
+-- +----+-------+--------+---------+---------+-------+----------------+----------------+
+-- | id |count| amount| title    | author   | price | img_path       | order_id       |
+-- +----+-------+--------+------------+----------+-------+----------------+----------------+
+-- |  1 |   1 |  27.20| 解忧杂货店 | 东野圭吾 | 27.20 | static/img/default.jpg|15294258455691 |
+-- |  2 |   1 |  23.00| 边城      | 沈从文   | 23.00 | static/img/default.jpg|15294258455691 |
+INSERT INTO order_items VALUES(1,1,27.20,'解忧杂货店','东野圭吾',27.20,'static/img/default.jpg',15294258455691),
+(2,1,23.00,'边城','沈从文',23.00,'static/img/default.jpg',15294258455692);
+DESC order_items;
+SELECT *FROM order_items;
+-- +----+-------+--------+------------+----------+-------+------------+----------------+
+```
\ No newline at end of file
-- 
Gitee