字符集和数据库的维护

前言

表的增删改查：

1️⃣ ：mysql环境准备

2️⃣ ：简单的表查询

3️⃣ ：通配符+正则表达式

4️⃣ ：mysql函数与分组

5️⃣ ：子查询_联结查询_组合查询

6️⃣ ：mysql全文本搜索

7️⃣ ：表的增删改查

一个一个小模块：

8️⃣ ：视图+存储过程+游标的简单使用

9️⃣ ：触发器+事务处理

🔟 ：字符集+校对+备份数据库+日志

第一部分：我们准备环境：安装数据库+创建数据库+创建用户+授权。

第二部分：环境准备好后，进行简单的单表查询：导入表+表查询。

第三部分：通配符和正则表达式，增强where的筛选功能。

第四部分：对列进行计算处理称为字段。复杂的字段用函数处理。按照不同组汇总，进行分组操作。

第五部分：在多表上进行查询：子查询+联结查询＋组合查询。

第六部分：mysql的全文本搜索。

第七部分：表的删改查。

前七部分组成表的增删改查。　之后都是一个一个小模块的介绍。

第八部分：视图是虚拟的表；存储过程是一条或多条MySQL语句的集合；对于填有数据的游标，根据需要取出（检索）各行；

第九部分：触发器使得某些语句在事件发生时自动执行；数据库的事务处理，可以保证保证成批的MySQL操作要么完全执行，要么完全不执行。

现在第十部分：参考《mysql必知必会》chapter 27~30,字符集＋数据库的维护。

文章目录

摘要与总结

我们的数据库需要适应不同的字符集，适应不同的排序和检索数据的方法。

数据库的备份和日志也是数据库操作中重要的一部分。

字符集与校对

世界各地，有不同的语言。

因而，我们的数据库需要适应不同的字符集，适应不同的排序和检索数据的方法。

一些术语：

字符集为字母和符号的集合；
编码为某个字符集成员的内部表示；
校对为规定字符如何比较的指令。

show create database crashcourse;

-- 查看所支持的字符集完整列表
show character set;

-- 所支持校对的完整列表
show collation;

-- 所用的字符集和校对
-- 区分大小写（由_cs表示），不区分大小写（由_ci表示）。
show variables like 'character%';
show variables like 'collation%';

-- 创建表的时候指定字符集和校对
-- utf8字符，不区分大小写
create table mytable(num int,name char(20))
default character set utf8 collate utf8_general_ci;
show create table mytable;

-- 排序的时候，暂时不区分大小写
-- 因为'collation%' 中没有utf8_general_cs
-- 至于如何增添字符集啥的，我不知道
-- 建表的时候，没有设置字符集，使用的是默认的字符集
show create table customers; 
show table status where Name='customers';
select * from customers
order by cust_name collate utf8_general_ci;

数据库的维护

数据库的备份

参考文章：备份和还原MySQL数据库的简便方法

由于MySQL数据库是基于磁盘的文件，普通的备份系统和例程就能备份MySQL的数据。但是，由于这些文件总是处于打开和使用状态，普通的文件副本备份不一定总是有效。

-- 备份
mysqldump -u root -p crashcourse > crashcourse_back.sql
-- 还原
mysql -u root -p crashcourse < crashcourse_back.sql

分析表、检查表和优化表

参考文章：分析表、检查表和优化表、MySQL不同存储引擎下optimize的用法

分析表主要作用是用来检查表键是否正确;检查表主要作用是检查表是否存在错误;优化表主要作用是消除删除或者更新造成的空间浪费。－－》啥作用，我不知道

-- 分析表
analyze TABLE orders;
-- 检查表
CHECK TABLE orders;
-- 优化表
optimize table orders;

-- mysql诊断启动问题
systemctl status mysqld

查看日志

参考：探究MySQL中的日志文件

错误日志
错误日志文件对MySQL的启动，运行，关闭过程进行了记录。
```
show variables like 'log_error'; -- 可以看到错误日志的路径和文件名
```
慢查询日志
慢查询日志用来记录响应时间超过阈值的SQL语句，所以我们可以设置一个阈值，将运行时间超过该值的所有SQL语句都记录到慢查询日志文件中。
```
show variables like "%slow%";  -- 可以看到慢查询日志的路径和文件名
show variables like 'long_query_time';　-- 显示阈值
```
查询日志
查看日志记录了所有对 MySQL 数据库请求的信息，不论这些请求是否得到了正确的执行。默认为主机名.log　-->这个是一个通用日志，啥都有
```
show variables like "general_log%";　-- 可以看到查询日志的路径和文件名
```
二进制日志
二进制日志记录了对数据库执行更改的所有操作，但是不包括select和show这类操作
```
show variables like 'datadir';
```

其他

这本书上没有索引章节，我们简单补充下。

MySQL创建索引，各种索引的创建及举例、MySQL 主键与索引的联系与区别

主键一定是唯一性索引，唯一性索引并不一定就是主键。

关于mysql的数据类型：这本书,目前使用的数据类型：int,char,decimal。

其他数据类型参考：MySQL 数据类型

我的链接中都使用了表，但是我并没有介绍表结构。因为比较麻烦。

介绍可以参考附录，脚本可以去官网下载。

下面为了完整性，唯一的一次，显示这两个脚本。

########################################
# MySQL Crash Course
# http://www.forta.com/books/0672327120/
# Example table creation scripts
########################################


########################
# Create customers table
########################
CREATE TABLE customers
(
  cust_id      int       NOT NULL AUTO_INCREMENT,
  cust_name    char(50)  NOT NULL ,
  cust_address char(50)  NULL ,
  cust_city    char(50)  NULL ,
  cust_state   char(5)   NULL ,
  cust_zip     char(10)  NULL ,
  cust_country char(50)  NULL ,
  cust_contact char(50)  NULL ,
  cust_email   char(255) NULL ,
  PRIMARY KEY (cust_id)
) ENGINE=InnoDB;

#########################
# Create orderitems table
#########################
CREATE TABLE orderitems
(
  order_num  int          NOT NULL ,
  order_item int          NOT NULL ,
  prod_id    char(10)     NOT NULL ,
  quantity   int          NOT NULL ,
  item_price decimal(8,2) NOT NULL ,
  PRIMARY KEY (order_num, order_item)
) ENGINE=InnoDB;


#####################
# Create orders table
#####################
CREATE TABLE orders
(
  order_num  int      NOT NULL AUTO_INCREMENT,
  order_date datetime NOT NULL ,
  cust_id    int      NOT NULL ,
  PRIMARY KEY (order_num)
) ENGINE=InnoDB;

#######################
# Create products table
#######################
CREATE TABLE products
(
  prod_id    char(10)      NOT NULL,
  vend_id    int           NOT NULL ,
  prod_name  char(255)     NOT NULL ,
  prod_price decimal(8,2)  NOT NULL ,
  prod_desc  text          NULL ,
  PRIMARY KEY(prod_id)
) ENGINE=InnoDB;

######################
# Create vendors table
######################
CREATE TABLE vendors
(
  vend_id      int      NOT NULL AUTO_INCREMENT,
  vend_name    char(50) NOT NULL ,
  vend_address char(50) NULL ,
  vend_city    char(50) NULL ,
  vend_state   char(5)  NULL ,
  vend_zip     char(10) NULL ,
  vend_country char(50) NULL ,
  PRIMARY KEY (vend_id)
) ENGINE=InnoDB;

###########################
# Create productnotes table
###########################
CREATE TABLE productnotes
(
  note_id    int           NOT NULL AUTO_INCREMENT,
  prod_id    char(10)      NOT NULL,
  note_date datetime       NOT NULL,
  note_text  text          NULL ,
  PRIMARY KEY(note_id),
  FULLTEXT(note_text)
) ENGINE=MyISAM;


#####################
# Define foreign keys
#####################
ALTER TABLE orderitems ADD CONSTRAINT fk_orderitems_orders FOREIGN KEY (order_num) REFERENCES orders (order_num);
ALTER TABLE orderitems ADD CONSTRAINT fk_orderitems_products FOREIGN KEY (prod_id) REFERENCES products (prod_id);
ALTER TABLE orders ADD CONSTRAINT fk_orders_customers FOREIGN KEY (cust_id) REFERENCES customers (cust_id);
ALTER TABLE products ADD CONSTRAINT fk_products_vendors FOREIGN KEY (vend_id) REFERENCES vendors (vend_id);

########################################
# MySQL Crash Course
# http://www.forta.com/books/0672327120/
# Example table population scripts
########################################


##########################
# Populate customers table
##########################
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10001, 'Coyote Inc.', '200 Maple Lane', 'Detroit', 'MI', '44444', 'USA', 'Y Lee', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES(10002, 'Mouse House', '333 Fromage Lane', 'Columbus', 'OH', '43333', 'USA', 'Jerry Mouse');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10003, 'Wascals', '1 Sunny Place', 'Muncie', 'IN', '42222', 'USA', 'Jim Jones', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact, cust_email)
VALUES(10004, 'Yosemite Place', '829 Riverside Drive', 'Phoenix', 'AZ', '88888', 'USA', 'Y Sam', '[email protected]');
INSERT INTO customers(cust_id, cust_name, cust_address, cust_city, cust_state, cust_zip, cust_country, cust_contact)
VALUES(10005, 'E Fudd', '4545 53rd Street', 'Chicago', 'IL', '54545', 'USA', 'E Fudd');


########################
# Populate vendors table
########################
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1001,'Anvils R Us','123 Main Street','Southfield','MI','48075', 'USA');
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1002,'LT Supplies','500 Park Street','Anytown','OH','44333', 'USA');
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1003,'ACME','555 High Street','Los Angeles','CA','90046', 'USA');
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1004,'Furball Inc.','1000 5th Avenue','New York','NY','11111', 'USA');
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1005,'Jet Set','42 Galaxy Road','London', NULL,'N16 6PS', 'England');
INSERT INTO vendors(vend_id, vend_name, vend_address, vend_city, vend_state, vend_zip, vend_country)
VALUES(1006,'Jouets Et Ours','1 Rue Amusement','Paris', NULL,'45678', 'France');


#########################
# Populate products table
#########################
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('ANV01', 1001, '.5 ton anvil', 5.99, '.5 ton anvil, black, complete with handy hook');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('ANV02', 1001, '1 ton anvil', 9.99, '1 ton anvil, black, complete with handy hook and carrying case');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('ANV03', 1001, '2 ton anvil', 14.99, '2 ton anvil, black, complete with handy hook and carrying case');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('OL1', 1002, 'Oil can', 8.99, 'Oil can, red');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('FU1', 1002, 'Fuses', 3.42, '1 dozen, extra long');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('SLING', 1003, 'Sling', 4.49, 'Sling, one size fits all');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('TNT1', 1003, 'TNT (1 stick)', 2.50, 'TNT, red, single stick');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('TNT2', 1003, 'TNT (5 sticks)', 10, 'TNT, red, pack of 10 sticks');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('FB', 1003, 'Bird seed', 10, 'Large bag (suitable for road runners)');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('FC', 1003, 'Carrots', 2.50, 'Carrots (rabbit hunting season only)');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('SAFE', 1003, 'Safe', 50, 'Safe with combination lock');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('DTNTR', 1003, 'Detonator', 13, 'Detonator (plunger powered), fuses not included');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('JP1000', 1005, 'JetPack 1000', 35, 'JetPack 1000, intended for single use');
INSERT INTO products(prod_id, vend_id, prod_name, prod_price, prod_desc)
VALUES('JP2000', 1005, 'JetPack 2000', 55, 'JetPack 2000, multi-use');



#######################
# Populate orders table
#######################
INSERT INTO orders(order_num, order_date, cust_id)
VALUES(20005, '2005-09-01', 10001);
INSERT INTO orders(order_num, order_date, cust_id)
VALUES(20006, '2005-09-12', 10003);
INSERT INTO orders(order_num, order_date, cust_id)
VALUES(20007, '2005-09-30', 10004);
INSERT INTO orders(order_num, order_date, cust_id)
VALUES(20008, '2005-10-03', 10005);
INSERT INTO orders(order_num, order_date, cust_id)
VALUES(20009, '2005-10-08', 10001);


###########################
# Populate orderitems table
###########################
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 1, 'ANV01', 10, 5.99);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 2, 'ANV02', 3, 9.99);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 3, 'TNT2', 5, 10);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20005, 4, 'FB', 1, 10);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20006, 1, 'JP2000', 1, 55);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20007, 1, 'TNT2', 100, 10);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20008, 1, 'FC', 50, 2.50);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 1, 'FB', 1, 10);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 2, 'OL1', 1, 8.99);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 3, 'SLING', 1, 4.49);
INSERT INTO orderitems(order_num, order_item, prod_id, quantity, item_price)
VALUES(20009, 4, 'ANV03', 1, 14.99);

#############################
# Populate productnotes table
#############################
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(101, 'TNT2', '2005-08-17',
'Customer complaint:
Sticks not individually wrapped, too easy to mistakenly detonate all at once.
Recommend individual wrapping.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(102, 'OL1', '2005-08-18',
'Can shipped full, refills not available.
Need to order new can if refill needed.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(103, 'SAFE', '2005-08-18',
'Safe is combination locked, combination not provided with safe.
This is rarely a problem as safes are typically blown up or dropped by customers.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(104, 'FC', '2005-08-19',
'Quantity varies, sold by the sack load.
All guaranteed to be bright and orange, and suitable for use as rabbit bait.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(105, 'TNT2', '2005-08-20',
'Included fuses are short and have been known to detonate too quickly for some customers.
Longer fuses are available (item FU1) and should be recommended.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(106, 'TNT2', '2005-08-22',
'Matches not included, recommend purchase of matches or detonator (item DTNTR).'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(107, 'SAFE', '2005-08-23',
'Please note that no returns will be accepted if safe opened using explosives.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(108, 'ANV01', '2005-08-25',
'Multiple customer returns, anvils failing to drop fast enough or falling backwards on purchaser. Recommend that customer considers using heavier anvils.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(109, 'ANV03', '2005-09-01',
'Item is extremely heavy. Designed for dropping, not recommended for use with slings, ropes, pulleys, or tightropes.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(110, 'FC', '2005-09-01',
'Customer complaint: rabbit has been able to detect trap, food apparently less effective now.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(111, 'SLING', '2005-09-02',
'Shipped unassembled, requires common tools (including oversized hammer).'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(112, 'SAFE', '2005-09-02',
'Customer complaint:
Circular hole in safe floor can apparently be easily cut with handsaw.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(113, 'ANV01', '2005-09-05',
'Customer complaint:
Not heavy enough to generate flying stars around head of victim. If being purchased for dropping, recommend ANV02 or ANV03 instead.'
);
INSERT INTO productnotes(note_id, prod_id, note_date, note_text)
VALUES(114, 'SAFE', '2005-09-07',
'Call from individual trapped in safe plummeting to the ground, suggests an escape hatch be added.
Comment forwarded to vendor.'
);