MySQL基础知识：创建MySQL数据库和表

虚构一个微型在线书店的数据库和数据，作为后续MySQL脚本的执行源，方便后续MySQL和SQL的练习。

在虚构这个库的过程中，主要涉及的是如何使用命令行管理 MySQL数据库对象：数据库、表、索引、外键等；另一个更为重要的是如何Mock对应表的数据。

虚构书店数据库的dump脚本：Github

数据库（Database）

将要创建的虚拟书店的数据库名为： mysql_practice;

创建数据库的语法：

CREATE DATABASE [IF NOT EXISTS] database_name
[CHARACTER SET charset_name]
[COLLATE collation_name]

1. IF NOT EXISTS： 可选项，避免数据库已经存在时报错。
2. CHARACTER SET：可选项，不指定的时候会默认给个。
   • 查看当前MySQL Server支持的字符集(character set):

     show character set; -- 方法1
     show charset; -- 方法2
     show char set; -- 方法3
     

3. COLLATE：针对特定character set比较字符串的规则集合；可选项，不指定的时候会默认给个。
   • 获取 charater set的 collations

     show collation like 'utf8%';
     

   • collation名字的规则： charater_set_name_ci 或者 charater_set_name_cs 或 charater_set_name_bin；_ci表示不区分大小写，_cs表示区分大小写；_bin表示用编码值比较。
4. 示例：

   CREATE DATABASE my_test_tb CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;
   

TODO： 关于 character set和collations，内容稍微有点多，后面会单独记一篇文章。

登录的时候选择数据库

mysql -uroot -D database_name -p

登录后选择数据库

use database_name;

查看当前选的数据库

select database();

创建新数据库

create database if not exists mysql_practice;

通过下面的语句可以检查创建的数据库：

show create database mysql_practice;

可以看到，如果创建数据库时候没有指定 character set 和 collate 的话，会默认指定一套。

显示所有当前账户可见的数据库

show databases;

删除数据库

drop database if exists mysql_practice;

MySQL中 schema 是 database 的同义词，因此也可以使用下面语句删除数据库：

drop schema if exists mysql_practice;

数据表（Table）

MySQL创建数据表的语法

CREATE TABLE [IF NOT EXISTS] table_name(
   column_1_definition,
   column_2_definition,
   ...,
   table_constraints
) ENGINE=storage_engine;

表列的定义语法：

column_name data_type(length) [NOT NULL] [DEFAULT value] [AUTO_INCREMENT] column_constraint;

表的约束（Table Constraints）: UNIQUE, CHECK, PRIMARY KEY and FOREIGN KEY.

查看表的定义

desc table_name;

创建mysql_practice数据表

USE mysql_practice;

DROP TABLE IF EXISTS customer_order;
DROP TABLE IF EXISTS book;
DROP TABLE IF EXISTS book_category;
DROP TABLE IF EXISTS customer_address;
DROP TABLE IF EXISTS customer;
DROP TABLE IF EXISTS region;

-- region，数据使用: https://github.com/xiangyuecn/AreaCity-JsSpider-StatsGov
CREATE TABLE IF NOT EXISTS region(
	id INT AUTO_INCREMENT,
    pid INT NOT NULL,
    deep INT NOT NULL,
    name VARCHAR(200) NOT NULL,
    pinyin_prefix VARCHAR(10) NOT NULL,
    pinyin VARCHAR(200) NOT NULL,
    ext_id VARCHAR(100) NOT NULL,
    ext_name VARCHAR(200) NOT NULL,
    PRIMARY KEY(id)
);

-- customer
CREATE TABLE IF NOT EXISTS customer(
    id INT AUTO_INCREMENT,
    no VARCHAR(50) NOT NULL,
    first_name VARCHAR(255) NOT NULL,
	last_name VARCHAR(255) NOT NULL,
    status VARCHAR(20) NOT NULL,
    phone_number VARCHAR(20)  NULL,
    updated_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL,
    PRIMARY KEY(id),
    unique(no)
) ENGINE=INNODB;

-- customer address
CREATE TABLE IF NOT EXISTS customer_address(
	id INT AUTO_INCREMENT,
    customer_id INT NOT NULL,
    area_id INT NULL,
    address_detail VARCHAR(200) NULL,
	is_default bit NOT NULL,
	updated_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL,
    PRIMARY KEY(id),
    FOREIGN KEY(customer_id) REFERENCES customer (id) ON UPDATE RESTRICT ON DELETE CASCADE
) ENGINE=INNODB;

-- book category
CREATE TABLE IF NOT EXISTS book_category(
	id INT AUTO_INCREMENT,
    code VARCHAR(200) NOT NULL,
	name VARCHAR(200) NOT NULL,
    parent_id INT NULL,
    deep INT NULL,
	updated_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL,
    PRIMARY KEY(id)
);

-- book
CREATE TABLE IF NOT EXISTS book(
	id INT AUTO_INCREMENT,
    category_id INT NOT NULL,
    no VARCHAR(50) NOT NULL,
    name VARCHAR(200) NOT NULL,
    status VARCHAR(50) NOT NULL,
    unit_price DOUBLE NOT NULL,
    author VARCHAR(50)  NULL,
    publish_date DATETIME NULL,
    publisher VARCHAR(200) NOT NULL,
	updated_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL,
    PRIMARY KEY(id),
    FOREIGN KEY (category_id) REFERENCES book_category (id) ON UPDATE RESTRICT ON DELETE CASCADE
);

-- orders
CREATE TABLE IF NOT EXISTS customer_order(
	id INT AUTO_INCREMENT,
    no VARCHAR(50) NOT NULL,
    customer_id INT NOT NULL,
    book_id INT NOT NULL,
    quantity INT NOT NULL,
    total_price DOUBLE NOT NULL,
    discount DOUBLE NULL,
    order_date DATETIME NOT NULL,
	updated_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL,
    PRIMARY KEY(id),
    FOREIGN KEY (customer_id) REFERENCES customer(id) ON UPDATE RESTRICT ON DELETE CASCADE,
    FOREIGN KEY (book_id) references book (id) on update restrict on delete cascade
) ENGINE=INNODB;

导入region数据

下载region csv数据：【三级】省市区 数据下载.

导入语句：

LOAD DATA INFILE '/tmp/ok_data_level3.csv'
INTO TABLE region
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS;

导入如果报错：

ERROR 1290 (HY000): The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

• 通过命令 mdfind -name my.cnf 找到mysql配置文件 my.cnf；
• 解决办法 (还没实际测试过，大都使用的是 LOATA DATA LOCAL INFILE 方式)

或者使用 LOAD DATA LOCAL INFILE代替 LOAD DATA INFILE 即：

LOAD DATA LOCAL INFILE '/tmp/ok_data_level3.csv'
INTO TABLE region
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS;

如果报错：

Error Code: 3948. Loading local data is disabled; this must be enabled on both the client and server sides

或者报错:

ERROR 1148 (42000): The used command is not allowed with this MySQL version

• 查看配置: show variables like "local_infile";
• 修改配置: set global local_infile = 1;

生成Customer数据

创建一个SP：

USE mysql_practice;

DROP PROCEDURE IF EXISTS sp_generate_customers;

DELIMITER $$

CREATE PROCEDURE sp_generate_customers()
BEGIN

-- Generate 10000 customer and customer_address

set @fNameIndex = 1;
set @lNameIndex = 1;

loop_label_f: LOOP

	IF @fNameIndex > 100 THEN
		LEAVE loop_label_f;
	END IF;

    set @fName = ELT(@fNameIndex, "James","Mary","John","Patricia","Robert","Linda","Michael","Barbara","William","Elizabeth","David","Jennifer","Richard","Maria","Charles","Susan","Joseph","Margaret","Thomas","Dorothy","Christopher","Lisa","Daniel","Nancy","Paul","Karen","Mark","Betty","Donald","Helen","George","Sandra","Kenneth","Donna","Steven","Carol","Edward","Ruth","Brian","Sharon","Ronald","Michelle","Anthony","Laura","Kevin","Sarah","Jason","Kimberly","Matthew","Deborah","Gary","Jessica","Timothy","Shirley","Jose","Cynthia","Larry","Angela","Jeffrey","Melissa","Frank","Brenda","Scott","Amy","Eric","Anna","Stephen","Rebecca","Andrew","Virginia","Raymond","Kathleen","Gregory","Pamela","Joshua","Martha","Jerry","Debra","Dennis","Amanda","Walter","Stephanie","Patrick","Carolyn","Peter","Christine","Harold","Marie","Douglas","Janet","Henry","Catherine","Carl","Frances","Arthur","Ann","Ryan","Joyce","Roger","Diane");

		loop_label_last: LOOP

		IF @lNameIndex > 100 THEN
			LEAVE loop_label_last;
		END IF;

			SET @lName =  ELT(@lNameIndex, "Smith","Johnson","Williams","Jones","Brown","Davis","Miller","Wilson","Moore","Taylor","Anderson","Thomas","Jackson","White","Harris","Martin","Thompson","Garcia","Martinez","Robinson","Clark","Rodriguez","Lewis","Lee","Walker","Hall","Allen","Young","Hernandez","King","Wright","Lopez","Hill","Scott","Green","Adams","Baker","Gonzalez","Nelson","Carter","Mitchell","Perez","Roberts","Turner","Phillips","Campbell","Parker","Evans","Edwards","Collins","Stewart","Sanchez","Morris","Rogers","Reed","Cook","Morgan","Bell","Murphy","Bailey","Rivera","Cooper","Richardson","Cox","Howard","Ward","Torres","Peterson","Gray","Ramirez","James","Watson","Brooks","Kelly","Sanders","Price","Bennett","Wood","Barnes","Ross","Henderson","Coleman","Jenkins","Perry","Powell","Long","Patterson","Hughes","Flores","Washington","Butler","Simmons","Foster","Gonzales","Bryant","Alexander","Russell","Griffin","Diaz","Hayes");

			-- insert into customer
			INSERT INTO customer(no, first_name, last_name, status, phone_number, updated_at, created_at)
            values(
				REPLACE(LEFT(uuid(), 16), '-', ''),
				@fName,
				@lName,
				'ACTIVE',
				null,
				curdate(),
				curdate()
            );

            -- insert into customer_address
            set @randomArea = 0;
            SELECT id into @randomArea FROM region where deep = 2 ORDER BY RAND() LIMIT 1;

            INSERT INTO customer_address(customer_id, area_id, address_detail, is_default, updated_at, created_at)
            VALUES(
				@@Identity,
                @randomArea,
                '',
                1,
                curdate(),
                curdate()
            );

			set @lNameIndex = @lNameIndex + 1;

		END LOOP loop_label_last;

	SET @lNameIndex = 1; -- Note: assign 1 to last name index, for next loop.
	SET @fnameIndex = @fnameIndex + 1;

END LOOP loop_label_f;

-- update address_detail in customer_address
UPDATE customer_address ca
JOIN region r on ca.area_id = r.id and r.deep = 2
join region r2 on r.pid = r2.id and r2.deep = 1
join region r3 on r2.pid = r3.id and r3.deep = 0
SET ca.address_detail = concat(r3.ext_name, r2.ext_name, r.ext_name);

END $$

DELIMITER ;

调用SP:

call sp_generate_customers();

生成产品分类和产品数据

第零步： 手动插入产品分类到product_category表中

INSERT INTO product_category(code,name, parent_id, deep, updated_at, created_at)
VALUES
('BOOK', 'Book', 0, 0, curdate(), curdate()),
('BOOK_CODE', 'Code Book', 1, 1, curdate(), curdate()),
('BOOK_CHIDREN', 'Children Book', 1, 1, curdate(), curdate()),
('BOOK_SCIENCE', 'Science Book', 1, 1, curdate(), curdate());

第一步： 用Python写个爬虫工具，抓取书店的商品信息。

下面是抓取当当搜索“科学”关键字的书籍列表。

import requests
import csv
from bs4 import BeautifulSoup

def crawl(url):
    res = requests.get(url)
    res.encoding = 'gb18030'
    soup = BeautifulSoup(res.text, 'html.parser')
    n = 0
    section = soup.find('ul', id='component_59')
    allLIs = section.find_all('li')
    #print(allLIs)
    with open('output_science.csv', 'w', encoding='utf8') as f:
        csv_writer = csv.writer(f, delimiter='#') # 由于内容里有','，因此这里指定'#'作为csv分隔符
        csv_writer.writerow(['序号', '书名', '价格', '作者', '出版时间', '出版社'])

        for books in allLIs:
            title = books.select('.name')[0].text.strip().split(' ', 1)[0].strip()
            price = books.select('.search_pre_price')[0].text.strip('¥')
            authorInfo = books.select('.search_book_author')[0].text.strip().split('/')
            author = authorInfo[0]
            publishDate = authorInfo[1]
            publisher = authorInfo[2]
            n += 1
            csv_writer.writerow([n, title, price, author, publishDate, publisher])

url = 'http://search.dangdang.com/?key=%BF%C6%D1%A7&act=input'
crawl(url)

第二步： 导入csv数据到MySQL数据表mock_science中。

CREATE TABLE `mock_science` (
  `id` int(11) NOT NULL,
  `name` varchar(200) DEFAULT NULL,
  `price` double DEFAULT NULL,
  `author` varchar(100) DEFAULT NULL,
  `publish_date` varchar(100) DEFAULT NULL,
  `publisher` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

第三步： 插入科学类书信息到product表中

INSERT book(category_id, no, name, status,unit_price, author,publish_date,publisher, updated_at, created_at)
SELECT
4,
REPLACE(LEFT(uuid(), 16), '-', ''),
name,
'ACTIVE',
price,
author,
publish_date,
publisher,
curdate(),
curdate()
FROM
mock_science;

循环第一到第三步，可以插入更多的产品信息。练习数据库最终抓取了JAVA，儿童，科学三个关键搜索出的第一页书籍。

生成订单数据

随机生成订单数据的SP(注意：这个sp生成的数据，还需要进一步处理):

USE mysql_practice;

DROP PROCEDURE IF EXISTS sp_generate_orders;

DELIMITER $$

-- Reference: https://www.mysqltutorial.org/select-random-records-database-table.aspx
-- Generate orders for last two years.
-- each day have orders range: [500, 5000]
CREATE PROCEDURE sp_generate_orders()
BEGIN

SET @startDate = '2020-03-01';
SET @endDate = curdate();

loop_label_p: LOOP

	IF @startDate > @endDate THEN
		LEAVE loop_label_p;
    END IF;

	SET @randCustomerTotal = FLOOR(RAND()*50) + 100;
    SET @randBookTotal = FLOOR(RAND()*5) + 1;

	SET @randQty = FLOOR(RAND()*3) + 1;

	SET @query1 = CONCAT('INSERT INTO customer_order(no, customer_id, book_id, quantity, total_price,discount, order_date, updated_at, created_at)');
    SET @query1 = CONCAT(@query1, ' select ', "'", uuid(), "'",', c.id, p.id,', @randQty, ', 0, 0, ', "'",@startDate,"'", ',', "'",curdate(),"'" ,',', "'",curdate(),"'");
    SET @query1 = CONCAT(@query1, ' FROM (select id from customer ORDER BY RAND() LIMIT ', @randCustomerTotal,') c  join ');
    SET @query1 = CONCAT(@query1, '  (select id from book order by rand() limit ', @randBookTotal,') p ');
    SET @query1 = CONCAT(@query1, 'where c.id is not null');

	PREPARE increased FROM @query1;
	EXECUTE increased;

    SET @startDate = DATE_ADD(@startDate,  INTERVAL 1 DAY);

END LOOP loop_label_p;

END $$

DELIMITER ;

总共会生成几十万或上百万条order数据；最好先简单加下index，不然query太慢，可以在创建db table后就加上。

添加index:

ALTER TABLE book ADD INDEX idx_unit_price(unit_price);

ALTER TABLE customer_order ADD INDEX idx_order_no(no);
ALTER TABLE customer_order ADD INDEX idx_order_date(order_date);
ALTER TABLE customer_order ADD INDEX idx_quantity(quantity);

更新order no:

-- update order total_price
-- please note it is better to add index first. otherwise it will be slow.

-- update order_no
update customer_order
set no = concat(REPLACE(LEFT(no, 16), '-', ''), customer_id, book_id)
where no is not null;
-- update total price

如果不想有重复的order no，可以通过下面的sql更新order no:

-- 处理重复的 order no
update customer_order co
join
(select no from customer_order co2 group by co2.no having count(*) > 1) as cdo
on co.no = cdo.no
set co.no = concat(REPLACE(LEFT(uuid(), 16), '-', ''), customer_id, book_id);

如果还有重复的order no，继续run上面这个sql，直到没有重复的即可。

更新order表里的total_price:

-- update total price
update customer_order co
join book b
on co.book_id = b.id
SET co.total_price = co.quantity * b.unit_price;

至此，我们的数据库表和对应的mock数据已经基本完成。使用mysqldump备份一下：

mysqldump -u [username] –p[password] [database_name] > [dump_file.sql]

下一步

• 视图（View）
• 存储过程（Store Procedure）
• 函数（Function）
• 触发器（Trigger）
• 定时任务（Job）

参考资料

1. MySQL Character Set
2. MySQL Collation
3. Generating random names in MySQL
4. MySQL LOOP
5. MySQL Select Random Records

原文地址：MySQL基础知识：创建MySQL数据库和表