mysql基础
1. 关系型数据库介绍
1.1 数据结构模型
数据结构模型主要有： 层次模型、网状结构、关系模型
关系模型：
- 二维关系：row，column
数据库管理系统：DBMS
关系型数据库管理系统：Relational，RDBMS
1.2 RDBMS专业名词
常见的关系型数据库管理系统：
- MySQL：MySQL，MariaDB，Percona-Server
- PostgreSQL：简称为pgsql
- Oracle
- MSSQL
SQL： Structure Query Language，结构化查询语言
约束： constraint，向数据表提供的数据要遵守的限制
- 主键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。且必须提供数据，不能为空（NOT NULL）。
- 一个表只能存在一个
- 惟一键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。允许为空（NULL）
- 一个表可以存在多个
- 外键约束：一个表中的某字段可填入数据取决于另一个表的主键已有的数据
- 检查性约束
索引： 将表中的一个或多个字段中的数据复制一份另存，并且这些数据需要按特定次序排序存储
1.3 关系型数据库的常见组件
关系型数据库的常见组件有：
数据库database、表：table，由行（row）和列（column）组成、索引：index、视图：view、用户：user、权限：privilege、存储过程：procedure、存储函数：function、触发器：trigger、事件调度器：event scheduler
1.4 SQL语句
SQL语句有三种类型：
- DDL：Data Defination Language，数据定义语言
- CREATE：创建
- DROP：删除
- ALTER：修改
- DML：Data Manipulation Language，数据操纵语言
- INSERT：向表中插入数据
- DELETE：删除表中数据
- UPDATE：更新表中数据
- SELECT：查询表中数据
- DCL：Data Control Language，数据控制语言
- GRANT：授权
- REVOKE：移除授权
2. mysql安装与配置
2.1 mysql安装
mysql安装方式有三种：
- 源代码：编译安装
- 二进制格式的程序包：展开至特定路径，并经过简单配置后即可使用
- 程序包管理器管理的程序包：
- rpm：有两种
- OS Vendor：操作系统发行商提供的
- 项目官方提供的
- deb
- rpm：有两种
#配置mysql的yum源
wget -O /usr/src/mysql57-community-release-el7-10.noarch.rpm \
http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
rpm -Uvh /usr/src/mysql57-community-release-el7-10.noarch.rpm
#安装mysql5.7
yum -y install mysql-community-server mysql-community-client \
mysql-community-common mysql-community-devel
#配置mysql的yum源
[root@node01-linux ~]# yum -y install wget
···
[root@node01-linux ~]# wget -O /usr/src/mysql57-community-release-el7-10.noarch.rpm http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
[root@node01-linux ~]# rpm -Uvh /usr/src/mysql57-community-release-el7-10.noarch.rpm
warning: /usr/src/mysql57-community-release-el7-10.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Preparing... ################################# [100%]
Updating / installing...
1:mysql57-community-release-el7-10 ################################# [100%]
#安装mysql5.7
[root@node01-linux ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel
···
Installed:
mysql-community-client.x86_64 0:5.7.30-1.el7
mysql-community-common.x86_64 0:5.7.30-1.el7
mysql-community-devel.x86_64 0:5.7.30-1.el7
mysql-community-libs.x86_64 0:5.7.30-1.el7
mysql-community-libs-compat.x86_64 0:5.7.30-1.el7
mysql-community-server.x86_64 0:5.7.30-1.el7
Dependency Installed:
net-tools.x86_64 0:2.0-0.25.20131004git.el7
Dependency Updated:
postfix.x86_64 2:2.10.1-9.el7
Replaced:
mariadb-libs.x86_64 1:5.5.56-2.el7
Complete!
2.2 mysql配置
#启动mysql并设置开机自动启动
[root@node01-linux ~]# systemctl enable --now mysqld
[root@node01-linux ~]# systemctl status mysqld
#确保3306端口已经监听起来
[root@node01-linux ~]# ss -antl
#在日志文件中找出临时密码
[root@node01-linux ~]# grep "password" /var/log/mysqld.log
#使用获取到的临时密码登录mysql
[root@node01-linux ~]# mysql -uroot -p'ykp<ibcSF5ra'
或者
[root@node01-linux ~]# mysql -uroot -p
Enter password: //此处输入密码，可以直接复制你的密码粘贴至此处，也可手动输入
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.30
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> //看到有这样的标识符则表示成功登录了
//修改mysql登录密码
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.01 sec)
mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'mysql123456';
Query OK, 0 rows affected (0.01 sec)
mysql> quit
Bye
//为避免mysql自动升级，这里需要卸载最开始安装的yum源
[root@node01-linux ~]# rpm -e mysql57-community-release
2.3 mariadb安装与配置
安装mariadb相关包
[root@node02-linux ~]# yum -y install mariadb*
2.4 mariadb安装与配置
#启动mariadb并设置开机自动启动
[root@node02-linux ~]# systemctl enable --now mariadb
[root@node02-linux ~]# systemctl status mariadb
#确保3306端口已经监听起来
#默认root账户登陆，不需要密码
[root@node02-linux ~]# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.65-MariaDB MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> quit
Bye
//修改mariadb登录密码，用password函数加密
MariaDB [(none)]> set password = password('mysql123456');
//登陆
[root@node02-linux ~]# mysql -uroot -p'mysql123456'
MariaDB [(none)]> quit
Bye
3. mysql的程序组成
客户端
- mysql：CLI交互式客户端程序（ 图形化
navicat收费workbench免费开源 ） - mysql_secure_installation：安全初始化，强烈建议安装完以后执行此命令
- mysqldump：mysql备份工具
- mysqladmin
服务器端
- mysqld
3.1 mysql工具使用
//语法：mysql [OPTIONS] [database]
//常用的OPTIONS：
-uUSERNAME //指定用户名，默认为root
-hHOST //指定服务器主机，默认为localhost，推荐使用ip地址
-pPASSWORD //指定用户的密码
-P# //指定数据库监听的端口，这里的#需用实际的端口号代替，如-P3307
-V //查看当前使用的mysql版本
-e //不登录mysql执行sql语句后退出，常用于脚本
[root@node01-linux ~]# mysql -V
mysql Ver 14.14 Distrib 5.7.30, for Linux (x86_64) using EditLine wrapper
//mysql数据库设置远程连接权限
mysql> grant all on *.* to 'root'@192.168.67.131 identified by 'mysql123456';
[root@node01-linux ~]# mysql -uroot -p'mysql123456' -h192.168.67.131
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
//注意，不推荐直接在命令行里直接用-pPASSWORD的方式登录，而是使用-p选项，然后交互式输入密码
[root@node01-linux ~]# mysql -uroot -p -h192.168.67.131
Enter password: mysql123456
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
//不登录mysql执行sql语句后退出，常用于脚本
[root@node01-linux ~]# mysql -uroot -p -h192.168.67.131 -e 'show databases;'
Enter password:
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
[root@node01-linux ~]# mysql -uroot -p'mysql123456' -h192.168.67.131 -e 'use mysql;show tables'
mysql: [Warning] Using a password on the command line interface can be insecure.
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| engine_cost |
| event |
| func |
| general_log |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
[root@node01-linux ~]# mysql -uroot -p'mysql123456' -h192.168.67.131 -e 'use mysql;show tables'|grep plugin
mysql: [Warning] Using a password on the command line interface can be insecure.
plugin
3.2 服务器监听的两种socket地址
socket类型
ip socket:
- 默认监听在tcp的3306端口，支持远程通信
unix sock:
- 监听在sock文件上（/tmp/mysql.sock，/var/lib/mysql/mysql.sock）
- 仅支持本地通信
- server地址只能是：localhost，127.0.0.1
[root@node01-linux ~]# mysql -uroot -p'mysql123456' -S /var/lib/mysql/mysql.sock
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 25
Server version: 5.7.30 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> quit
Bye
4. mysql数据库操作
4.1 DDL操作
4.1.1 数据库操作
//创建数据库
//语法：CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库school
mysql> CREATE DATABASE IF NOT EXISTS school;
Query OK, 1 row affected (0.00 sec)
//查看当前实例有哪些数据库
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| school |
| sys |
+--------------------+
5 rows in set (0.01 sec)
//删除数据库
//语法：DROP DATABASE [IF EXISTS] 'DB_NAME';
//删除数据库shcool
mysql> DROP DATABASE IF EXISTS school;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
4.1.2 表操作
//创建表
//语法：CREATE TABLE table_name (col1 datatype 修饰符,col2 datatype 修饰符) ENGINE='存储引擎类型';
//在数据库wangqingge里创建表school
mysql> CREATE DATABASE school;
Query OK, 1 row affected (0.00 sec)
mysql> USE school
Database changed
mysql> CREATE TABLE linux (id int NOT NULL,name VARCHAR(50) NOT NULL,age tinyint NOT NULL);
Query OK, 0 rows affected (0.01 sec)
//查看当前数据库有哪些表
mysql> SHOW TABLES;
+------------------+
| Tables_in_school |
+------------------+
| linux |
+------------------+
1 row in set (0.00 sec)
//查看具体表的结构
mysql> DESC linux;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(50) | NO | | NULL | |
| age | tinyint(4) | NO | | NULL | |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.04 sec)
//查找数据
mysql> SELECT * FROM linux;
Empty set (0.00 sec)
//删除表
mysql> DROP TABLE linux;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)
4.1.3 用户操作
mysql用户帐号由两部分组成，如’USERNAME’@‘HOST’，表示此USERNAME只能从此HOST上远程登录
这里（‘USERNAME’@‘HOST’）的HOST用于限制此用户可通过哪些主机远程连接mysql程序，其值可为：
IP地址，如：172.16.12.129
通配符
- %：匹配任意长度的任意字符，常用于设置允许从任何主机登录
- _：匹配任意单个字符
//数据库用户创建
//语法：CREATE USER 'username'@'host' [IDENTIFIED BY 'password'];
//创建数据库用户linux
密码策略问题异常信息：
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> CREATE USER 'linux'@'127.0.0.1' IDENTIFIED BY 'linux123456';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
解决办法：
1、查看 mysql 初始的密码策略，
输入语句 “ SHOW VARIABLES LIKE 'validate_password%'; ” 进行查看，
mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+--------+
| Variable_name | Value |
+--------------------------------------+--------+
| validate_password_check_user_name | OFF |
| validate_password_dictionary_file | |
| validate_password_length | 8 |
| validate_password_mixed_case_count | 1 |
| validate_password_number_count | 1 |
| validate_password_policy | MEDIUM |
| validate_password_special_char_count | 1 |
+--------------------------------------+--------+
7 rows in set (0.01 sec)
2、首先需要设置密码的验证强度等级，设置 validate_password_policy 的全局参数为 LOW 即可，
输入设值语句 “ set global validate_password_policy=LOW; ” 进行设值，
mysql> set global validate_password_policy=LOW;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------+-------+
| validate_password_check_user_name | OFF |
| validate_password_dictionary_file | |
| validate_password_length | 8 |
| validate_password_mixed_case_count | 1 |
| validate_password_number_count | 1 |
| validate_password_policy | LOW |
| validate_password_special_char_count | 1 |
+--------------------------------------+-------+
7 rows in set (0.00 sec)
mysql> CREATE USER 'liunx'@'127.0.0.1' IDENTIFIED BY '12345678';
Query OK, 0 rows affected (0.00 sec)