diff --git "a/MySQL/20230220MySQL\347\254\254\344\270\200\346\254\241\344\275\234\344\270\232.md" "b/MySQL/20230220MySQL\347\254\254\344\270\200\346\254\241\344\275\234\344\270\232.md" new file mode 100644 index 0000000000000000000000000000000000000000..6ffedd445b03ec3a40fe5e17fcaf8c624808f30b --- /dev/null +++ "b/MySQL/20230220MySQL\347\254\254\344\270\200\346\254\241\344\275\234\344\270\232.md" @@ -0,0 +1,288 @@ +# 笔记 + +数据库（Database） + +定点 decimal默认（10,0）其他 同上 + +浮点 float double + +float（M，N）1 M表示限制整数+小数，一共只能存放M位长度，n限制小数的长度，如果小数部分超过了n会自动截断并四舍五入 + +字符串 + +固定长度的char默认是1，最大的是255 + +可变长度varchar(M)65535 这里的M不可以缺省 + +时间类型 date 年月日 time 时分秒 year datetime timestamp + +unsigned 无符号的 表示正数不能负数 + +null允许为空，not null 不允许为空 + +SQL语法 + +大小写不分 + +一般以；结尾 + +库名，表名，字段名(列名) 支持英文字母、-、数字 class two classTwo + +名称中，不要用空格 class two + +名称中，不能用SQL语句的关键字，create + +# 作业一 + +```java +-- 1、创建数据库test01_market +CREATE DATABASE test01_market; +USE test01_market; +-- 2、创建表格customers +CREATE TABLE customers( +c_num int(11), +c_name VARCHAR(50), +c_contact VARCHAR(50), +c_city VARCHAR(50), +c_birth date +); + +-- | 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 | +-- +-- **要求3：**将c_contact字段移动到c_birth字段后面 +ALTER TABLE customers MODIFY c_contact VARCHAR(50) AFTER c_birth; +-- **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 TO customers_info; +-- **要求8：**删除字段c_city +ALTER TABLE customers_info DROP c_city; +DESC customers_info; +``` + +# 作业二 + +```java +-- 1、创建数据库test02_library +-- +CREATE DATABASE test02_library; +USE test02_library; +-- 2、创建表格books +-- +ALTER DATABASE test02_library CHARSET utf8; +ALTER TABLE books CHARSET utf8; +CREATE TABLE books( +b_id int(11), +b_name VARCHAR(50), +authors VARCHAR(100), +price float, +pubdate year, +note VARCHAR(100), +num int(100) +); +DESC 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 | +-- +-- 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,'TalofAAA','Dickes',23,'1995','nove1',11); +-- 2）不指定字段名称插入第二记录 +-- +insert into books values (2,'EmmaT','janelure',35,'1993','joke',22); +-- 3）同时插入多条记录（剩下的所有记录） +-- +insert into books values (3,'StoryofJane','JaneTim',40,'2001','novel',0),(4,'LoveyDay','GeorgeByron',20,'2005','novel',30),(5,'Oldland','HonoreBlade',30,'2010','law',0),(6,'TheBattle','UptonSara',30,'1999','medicine',40),(7,'RoseHood','Richardhaggard',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='nove1'; +-- 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; +``` + +# 作业三 + +```java +-- 1、创建数据库test03_bookstore +-- +CREATE DATABASE test03_bookstore; +USE test03_bookstore; +ALTER DATABASE test02_library CHARSET utf8; +ALTER TABLE book CHARSET utf8; +-- 2、创建book表 +-- +CREATE TABLE book( + id int(11), + title varchar(100), + author varchar(100), + price double(11,2), + sales int(11), + stock int(11), + img_path varchar(100) +); +DESC book; +-- ```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 | | +-- +----------+--------------+------+-----+---------+----------------+ +-- ``` +-- +-- 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',27.2,102,98,'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 +-- +CREATE TABLE users( +id int(11), +username varchar(100), +password varchar(100), +email varchar(100) +); +-- ```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 | | +-- +----------+--------------+------+-----+---------+----------------+ +-- ``` +-- +-- 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'); +-- +-- 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 | | +-- +--------------+--------------+------+-----+---------+-------+ +-- ``` +-- +create table orders( +id varchar(100), +order_time datetime, +total_count int(11), +total_amount double(11,2), +state int(11), +user_id int(11) +); + +-- 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 ortetime VALUES ('15294258455691','2018-06-20 00:30:45',2,50.20,0,1); +-- +-- 5、创建订单明细表order_items +-- +-- ```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 | | +-- +----------+--------------+------+-----+---------+----------------+ +-- ``` +-- +create table order_items( +id int(11), +count int(11), +amount double(11,2), +title varchar(100), +author varchar(100), +price double(11,2), +img_path varchar(100), +order_id varchar(100) +); +-- 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','15294258455691'); + +``` +