diff --git "a/19\351\231\210\345\246\203/20230215 \346\225\260\346\215\256\345\272\223class3.md" "b/19\351\231\210\345\246\203/20230215 \346\225\260\346\215\256\345\272\223class3.md" new file mode 100644 index 0000000000000000000000000000000000000000..b4b5f9264c93ef8ae9f516421bae6278f70b20ea --- /dev/null +++ "b/19\351\231\210\345\246\203/20230215 \346\225\260\346\215\256\345\272\223class3.md" @@ -0,0 +1,72 @@ +# 1笔记 + +1. #关于MySQL 支持的数据类型中常用的 + -- 1 数值型：整数，小数。 + +2. float double 是浮点型小数，decimal是定点型小数 + +3. 关于小数(M,N):M限制的总长度（整数部分+小数部分），N小数点后数字的长度 + +4. 对于N 超出限制时，会截断并四舍五入，不足时，会以0补齐 + + ```mysql + create --创造 + INSERT INTO <表格> (字段) VALUES (数值); + select * from <>; --查询表格的所有数据-- + desc <>; --查看表格 + + ``` + + + + + + + +# 2作业 + +```mysql +/* + Navicat Premium Data Transfer + + Source Server : localhost_3306 + Source Server Type : MySQL + Source Server Version : 50737 + Source Host : localhost:3306 + Source Schema : class3 + + Target Server Type : MySQL + Target Server Version : 50737 + File Encoding : 65001 + + Date: 15/02/2023 20:35:38 +*/ + +SET NAMES utf8mb4; +SET FOREIGN_KEY_CHECKS = 0; + +-- ---------------------------- +-- Table structure for student +-- ---------------------------- +DROP TABLE IF EXISTS `student`; +CREATE TABLE `student` ( + `学号` int(11) NULL DEFAULT NULL, + `姓名` varchar(8) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, + `性别` set('女','男') CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT '', + `爱好` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, + `住址` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, + `联系方式` int(11) NULL DEFAULT NULL, + `邮箱` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL, + `QQ` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL +) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic; + +insert into student (`学号`,`姓名`,`性别`,`爱好`,`住址`,`联系方式`,`邮箱`,`QQ`) VALUES (`2244310119`,`陈妃`,`女`,`(在此填写)`,`(在此填写)`,`(在此填写)`,`(在此填写)`,`(在此填写)`); + +-- ---------------------------- +-- Records of student +-- ---------------------------- + +SET FOREIGN_KEY_CHECKS = 1; + +``` + diff --git "a/19\351\231\210\345\246\203/20230216 DDI.md" "b/19\351\231\210\345\246\203/20230216 DDI.md" new file mode 100644 index 0000000000000000000000000000000000000000..dccc3eb2f84f9d715b81fbc99429b7b7de58e56d --- /dev/null +++ "b/19\351\231\210\345\246\203/20230216 DDI.md" @@ -0,0 +1,185 @@ +# 笔记 + +1. 删除数据库 + + DROP DATABASE [IF EXISTS] 数据库名称; + +2. 查看某个数据库的详细定义 + + SHOW CREATE DATABASE 数据库名称; + +3. 修改数据库的编码 + + ALTER DATABASE 数据库名 CHARACTER SET 新的字符集名称 COLLATE 校对规则; + +4. 删除表格 + + DROP TABLE IF EXISTS 表名称; + +5. 修改表的字符集和校对规则 + + ALTER TABLE 表名称 CHARSET=新字符集 COLLATE=新校对规则; + +6. 增加一个字段 + + ALTER TABLE 表名称 ADD COLUMN 字段名 数据类型; + +7. 删除一个字段 + + ALTER TABLE 表名称 DROP COLUMN 字段名; + +8. 修改一个字段名称 + + ALTER TABLE 表名称 CHANGE 旧字段名称 新的字段名称 数据类型; + +9. 修改一个字段的数据类型 + + ALTER TABLE 表名称 MODIFY 字段名称 新数据类型; + +10. 重命名表 + + ALTER TABLE 表名称 RENAME TO 新名称; + + + +# 作业 + +```mysql +--第一题-- +use test01_market; + +SELECT * FROM customers; + +#3： +ALTER TABLE customers MODIFY c_contact VARCHAR ALTER c_birth; + +#4： +alter table customers alter column c_name varchar(70); +#alter table 表名 alter column 字段名 数据类型 + +#5：将c_contact字段改名为c_phone +alter table customers rename column c_contact to c_phone; + + +#6: +alter table customers add column c_gender char(1) not null after c_name; + +#7:将表名改为customers_info +rename table customers to customers_info; + + +#8: + + +--第二题-- + +CREATE UPDATE test02_library; + + +#| 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 | +USE test02_library; + +CREATE TABLE books( + b_id int(11) not null, + b_name VARCHAR(50) NOT NULL, + authors VARCHAR(100) NOT NULL, + price FLOAT NOTnull, + pubdate year NOT NULL, + note varchar(100), + num int(11)not NULL + ); +DESC books; + +#3： +# 1）： + insert into books(b_id,b_name,authors,price,pubdate,note,num) values (1,'Tal of AAA','Dickes',23,'1995','novel',11); +#2): + INSERT INTO books VALUES(2,'EmmaT','Jane Lnra',35,'1993','joke',22); +#3): + INSERT INTO books 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','mdicine',40),(7,'Rose Hood','Richard haggard',2008,'2088 cartoon',28); + # SELECT * FROM books; + + +#4： +UPDATE books set price = price + 5 WHERE note = 'novel'; + + +#5： +UPDATE books set price = 40 WHERE b_name = 'EmmaT'; + + +#6： +DELETE from books where num = 0; +SELECT * FROM books ; + +--第三题-- +#1): + CREATE DATABASE test03_bookstore; +#2): + USE test03_bookstore; + CREATE TABLE book( + id int(11)UNSIGNED auto_increment PRIMARY KEY not null, + title VARCHAR(100) NOT NULL, + authors 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; + + INSERT INTO book VALUES(1,'解忧杂货店','东野吾圭',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'); +# SELECT * FROM book; + +#3): +CREATE TABLE users( + id INT(11) UNSIGNED auto_increment PRIMARY key NOT null, + usersname VARCHAR(100) UNIQUE KEY NOT NULL, + 'password' VARCHAR(100) NOT null, + email VARCHAR(100) NULL + ); + DESC users; + + + INSERT INTO users VALUES(1,'admin',112233,'admin@mxdx.com'); +# SELECT * FROM users; + +#4): +CREATE TABLE orders( + id VARCHAR(109) PRIMARY KEY NOT NULL, + order_time DATETIME NOT NULL, + total_count INT(11) NOT NULL, + total_amount DOUBLE(11,2) NOT NULL, + state INT(11) NOT NULL, + user_idINT(11) not null + ); + DESC orders; + +INSERT INTO orders VALUES(152942258455691,'2018-06-20 00:30:45',2,50.20,0,1); +SELECT * FROM orders; + +#5): +CREATE TABLE order_items( +id INT(11) UNSIGNED auto increment PRIMARY key NOT null, +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) NOT NULL +); +DESC order_items; + +INSERT INTO orders_items VALUES( 1,1,27.20,'解忧杂货店','东野圭吾',27.20,'static/img/default.jpg|1', +15294258455691),(2,1,23.00,'边城','沈从文',23.00,'static/img/default.jpg',15294258455691); +``` +