目录
mysql基础
数据库
关系型数据库
：存储在硬盘
- mysql：5.7版本前是开源软件
- oracle： 商业软件
- mariadb： 开源软件，由mysql原班人马开发
- sqlserver 商业软件
- MSSQL： MicroSoft 微软sql
nosql
：存储在内存，变量的形式key=value
- redis
- memcache
- mongodb
- pgsql
sqlite
：数据是存放在“文件（数据文件）”中
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：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
- DML：Data Manipulation Language，数据操纵语言
- DCL：Data Control Language，数据控制语言
|SQL语句类型 |对应操作|
|— |: —–|
|DDL |CREATE：创建； DROP：删除；ALTER：修改；|
|DML |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 |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
配置mysql的yum源
1.下载mysql的yum repository
[root@localhost ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm
2.更新下载好的yum repository
[root@localhost ~]# rpm -Uvh mysql57-community-release-el7-11.noarch.rpm
3.查看/etc/yum.repos.d/下多了两个mysql的repo
[root@localhost ~]# ls /etc/yum.repos.d/
myrepo.repo mysql-community.repo mysql-community-source.repo
4.开始安装mysql，安装前先禁用默认的mysql模块
[root@localhost ~]# yum module disable mysql
[root@localhost ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel --nogpgcheck
2.2 mysql配置
启动mysql并设置开机自动启动
[root@localhost ~]# systemctl enable --now mysqld
查看3306端口已经监听
[root@localhost ~]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since Sun 2022-07-24 13:57:18 CST; 3min 9s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 2729 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 2679 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 2731 (mysqld)
Tasks: 27 (limit: 11201)
Memory: 316.4M
CGroup: /system.slice/mysqld.service
└─2731 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
Jul 24 13:57:14 localhost.localdomain systemd[1]: Starting MySQL Server...
Jul 24 13:57:18 localhost.localdomain systemd[1]: Started MySQL Server.
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
LISTEN 0 128 0.0.0.0:22 0.0.0.0:*
LISTEN 0 80 *:3306 *:*
LISTEN 0 128 [::]:22 [::]:*
在日志文件中找出临时密码
[root@localhost ~]# grep "password" /var/log/mysqld.log
2022-07-24T05:57:15.560498Z 1 [Note] A temporary password is generated for root@localhost: g>u%=yugt6gW
使用获取到的临时密码登录mysql，密码为 g>u%=yugt6gW
[root@localhost ~]# mysql -uroot -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or /g.
Your MySQL connection id is 3
Server version: 5.7.38
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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>
修改mysql登录密码
mysql> alter user 'root'@'localhost' identified by 'Luojialong123!';
Query OK, 0 rows affected (0.00 sec)
使用新密码登录mysql
[root@localhost ~]# mysql -uroot -pLuojialong123!
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 4
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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>
避免mysql自动升级,卸载最开始安装的yum源
[root@localhost ~]# rpm -e mysql57-community-release
3.mariadb安装与配置
3.1 mariadb安装
[root@localhost ~]# yum -y install mariadb*
[root@localhost ~]# systemctl enable --now mariadb
[root@localhost ~]# systemctl status mariadb
● mariadb.service - MariaDB 10.3 database server
Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: d>
Active: active (running) since Sun 2022-07-24 02:21:37 EDT; 19s ago
Docs: man:mysqld(8)
https://mariadb.com/kb/en/library/systemd/
Process: 7967 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, status=0>
Process: 7831 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mariadb.service (code=>
Process: 7806 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/S>
Main PID: 7936 (mysqld)
Status: "Taking your SQL requests now..."
Tasks: 30 (limit: 4615)
Memory: 103.9M
CGroup: /system.slice/mariadb.service
└─7936 /usr/libexec/mysqld --basedir=/usr
设置密码
[root@localhost ~]# mysql
Welcome to the MariaDB monitor. Commands end with ; or /g.
Your MariaDB connection id is 8
Server version: 10.3.28-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)]> set password = password('123456');
Query OK, 0 rows affected (0.000 sec)
MariaDB [(none)]> /q
Bye
测试登录
[root@localhost ~]# mysql -uroot -p123456
Welcome to the MariaDB monitor. Commands end with ; or /g.
Your MariaDB connection id is 9
Server version: 10.3.28-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)]>
原创文章，作者：Maggie-Hunter，如若转载，请注明出处：https://blog.ytso.com/tech/database/276697.html