NAME="CentOS Linux"VERSION="7 (Core)"ID="centos"ID_LIKE="rhel fedora"VERSION_ID="7"PRETTY_NAME="CentOS Linux 7 (Core)"ANSI_COLOR="0;31"CPE_NAME="cpe:/o:centos:centos:7"HOME_URL="https://www.centos.org/"BUG_REPORT_URL="https://bugs.centos.org/"CENTOS_MANTISBT_PROJECT="CentOS-7"CENTOS_MANTISBT_PROJECT_VERSION="7"REDHAT_SUPPORT_PRODUCT="centos"REDHAT_SUPPORT_PRODUCT_VERSION="7"
systemctl stop firewalldsystemctl status firewalld● firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled) Active: inactive (dead) Docs: man:firewalld(1)
直接在/root目录输入以下命令
setenforce 0
在/etc/selinux/config中设置selinux为disabled
# This file controls the state of SELinux on the system.# SELINUX= can take one of these three values:# enforcing - SELinux security policy is enforced.# permissive - SELinux prints warnings instead of enforcing.# disabled - No SELinux policy is loaded.SELINUX=disabled #改为disabled# SELINUXTYPE= can take one of three values:# targeted - Targeted processes are protected,# minimum - Modification of targeted policy. Only selected processes are protected. # mls - Multi Level Security protection.SELINUXTYPE=targeted
阿里云源+epel源
yum repolist
已加载插件:fastestmirrorDetermining fastest mirrors * base: mirrors.aliyun.com * epel: d2lzkl7pfhq30w.cloudfront.net * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com源标识 源名称 状态!base/7/x86_64 CentOS-7 - Base - mirrors.aliyun.com 10,072!epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64 13,791!extras/7/x86_64 CentOS-7 - Extras - mirrors.aliyun.com 526!updates/7/x86_64 CentOS-7 - Updates - mirrors.aliyun.com 6,173repolist: 30,562
如果没有epel源通过一下命令安装
yum -y install epel-release
cd /etc/yum.repos.d/ # 进入目录vim mariadb.repo # 编辑源文件
编辑内容如下
[mariadb]name=MariaDB# baseurl=https://mirror.mariadb.org/yum/10.5/centos7-amd64baseurl=https://mirror.mariadb.org/yum/10.11.17/rhel7-amd64/gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDBgpgcheck=1

# 使用yum进行安装yum -y install MariaDB-server MariaDB-client# 以下是安装完成的状态已加载插件:fastestmirror, prioritiesLoading mirror speeds from cached hostfile * base: mirrors.aliyun.com * epel: d2lzkl7pfhq30w.cloudfront.net * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com10201 packages excluded due to repository priority protections软件包 MariaDB-server-10.11.9-1.el7.centos.x86_64 已安装并且是最新版本软件包 MariaDB-client-10.11.9-1.el7.centos.x86_64 已安装并且是最新版本无须任何处理

systemctl start mariadb #启动服务systemctl enable mariadb #设置开机启动systemctl restart mariadb #重新启动

使用ss查看是否启动
ss -taulanp | grep mariadb

mysql(mariadb)停止命令
systemctl stop mariadb #停止MariaDB

直接输入mysql或者输入mysql -uroot -p登录
输入mysql 直接进入不用输入初始密码

输入mysql -uroot -p进行登录 —— 初始密码为1

登录 MySQL 服务器后执行以下命令:
use mysql;update user set authentication_string=password('新密码') where user='root';flush privileges;exit;重新登录验证:
mysql -u root -p
在 Linux 终端执行:
mysqladmin -u root -p password '新密码'
MariaDB [(none)]> s--------------mysql Ver 15.1 Distrib 10.11.9-MariaDB, for Linux (x86_64) using readline 5.1Connection id: 4Current database:Current user: root@localhostSSL: Not in useCurrent pager: stdoutUsing outfile: ''Using delimiter: ;Server: MariaDBServer version: 10.11.9-MariaDB MariaDB ServerProtocol version: 10Connection: Localhost via UNIX socketServer characterset: latin1Db characterset: latin1Client characterset: utf8mb3Conn. characterset: utf8mb3UNIX socket: /var/lib/mysql/mysql.sockUptime: 2 min 42 secThreads: 1 Questions: 7 Slow queries: 0 Opens: 17 Open tables: 10 Queries per second avg: 0.043--------------

MariaDB [(none)]> quit;Bye
vim /etc/my.cnf
加入配置
[mysqld]character-set-server = utf8mb4collation-server = utf8mb4_unicode_ciinit_connect = 'SET NAMES utf8mb4'skip-character-set-client-handshake[client]default-character-set = utf8mb4[mysql]default-character-set = utf8mb4

systemctl restart mariadb

MariaDB [(none)]> s--------------mysql Ver 15.1 Distrib 10.11.9-MariaDB, for Linux (x86_64) using readline 5.1Connection id: 3Current database:Current user: root@localhostSSL: Not in useCurrent pager: stdoutUsing outfile: ''Using delimiter: ;Server: MariaDBServer version: 10.11.9-MariaDB MariaDB ServerProtocol version: 10Connection: Localhost via UNIX socketServer characterset: utf8mb4Db characterset: utf8mb4Client characterset: utf8mb4Conn. characterset: utf8mb4UNIX socket: /var/lib/mysql/mysql.sockUptime: 56 secThreads: 1 Questions: 4 Slow queries: 0 Opens: 17 Open tables: 10 Queries per second avg: 0.071--------------

show databases;

use mysql;

show tables;

方式一
describe user; --简写desc user;

方式二
show create table userG;
desc和show create table 都是用来查看表结构的但侧重点不通、使用场景等不同。
DESC 适合快速浏览字段的基础信息,SHOW CREATE TABLE 适合获取完整的建表语句和所有底层细节。
select database();

create database 库名;

先切换选择创建好的数据库
use auth;
再进行数据库的创建
创建users表
create table users( user_name char(16) not null, -- 创建用户名字段 user_passwd char(48) default '', -- 创建用户密码字段 primary key (user_name)); -- 设置主键

创建yonghu表
create table yonghu( name char(10), -- 创建用户名字段 passwd char(10), -- 创建用户密码字段 primary key (name)); -- 设置主键

insert into users values('冷莫溪','123.com'); 
使用select查看是否插入
select * from users;

(1)创建用户
create user lengmx identified by '123456';

(2)查询用户
方式一:使用select命令查询
select user,host,password from mysql.user;

方式二:使用show grants查询
show grants for 'lengmx'@'%';

(3)用户授权
授予权力,例如select
grant select on auth.* to 'lengmx'@'%';

使用show进行查询
show grants for 'lengmx'@'%';

(4)撤销用户授权
revoke select on auth.* from lengmx;show grants for 'lengmx'@'%';

mysqldump 是 MySQL 官方提供的逻辑备份工具,通过生成标准 SQL 语句文件实现数据库结构和数据的导出。支持单库、多库、单表或全库备份,默认输出到标准输出,需通过重定向保存为文件。
mkdir -pv /opt/mysql_bak

把之前创建的数据库auth备份到/opt/mysql_bak/ mysql_bak中
mysqldump -uroot -p auth > /opt/mysql_bak/auth_db.sql

验证备份文件:
使用wc和cat进行查看
wc -l < /opt/mysql_bak/auth_db.sqlcat /opt/mysql_bak/auth_db.sql


把之前创建的数据表user备份到/opt/mysql_bak/mysql_bak中
mysqldump -uroot -p auth users > /opt/mysql_bak/users_bak.sql

验证命令与上面数据库备份相同。
mysqldump -uroot -p --all-databases > /opt/mysql_bak/alldb.sql

du -sh /var/lib/mysql/

mysql -uroot -p
use auth;show tables;


DROP TABLE users;

查看删除后的表是否还在
show tables;

进入备份目录cd /opt/mysql_bak/,使用之前备份特定数据库的文件,然后恢复表
之前备份的命令进行改写(mysqldump换成mysql, > 换成 <)
mysql -uroot -p auth < /opt/mysql_bak/users_bak.sql;

验证恢复:
SHOW TABLES;SELECT * FROM users;

> 重定向输出,恢复时使用 < 重定向输入--single-transaction 参数避免锁表--no-data 仅备份结构--add-drop-table 在创建表前添加删除语句--skip-lock-tables 跳过锁表(可能影响一致性)--where 条件导出部分数据备份文件可通过压缩减少空间占用:
mysqldump -uroot -p dbname | gzip > backup.sql.gz

