1. 常见的数据库类型

关系型数据库 RDBMS： MySQL oracle PGSQL MSSQL
非关系型数据库 NoSQL： redis MongoDB(索引) ES(搜索引擎)
新型分布式解决方案 NewSQL： drds(阿里系产品)
https://db-engines.com/en/ranking 各大数据库使用排行

2. MySQL选型

一般选择官方主流版本:5.6,5.7 
GA（稳定发布版）
2019年4月13日发布的 5.7.26

官方下载地址推荐复制连接后，使用迅雷下载

选择的是二进制包

3. 安装

创建MySQL的数据目录
```
mkdir -p /data/mysql
```

把下载好的二进制包放到opt目录下(个人习惯)

yum -y install lrzsz (xshell使用的数据传输工具)
[root@localhost opt]# ls
mysql  mysql-5.7.26-linux-glibc2.12-x86_64.tar.gz

解压二进制包。并且更名

tar xf mysql-5.7.26-linux-glibc2.12-x86_64.tar.gz
mv mysql-5.7.26-linux-glibc2.12-x86_64 mysql
[root@localhost opt]# ls mysql
bin  COPYING  docs  include  lib  man  mysql.sock  mysql.sock.lock  README  share  support-files

修改环境变量

vi /etc/profile
export PATH=/opt/mysql/bin:$PATH

修改配置文件

#
[mysqld]
#数据目录
datadir=/data/mysql
#家目录
basedir=/opt/mysql
#套接字文件
socket=/opt/mysql/mysql.sock
#数据库服务管理用户
user=mysql
[mysql]
prompt=MySQL [\\d]>
[mysqld_safe]
log-error=/data/mysql/mysql.log
pid-file=/data/mysql/mysql.pid
[client]
port=3306
socket=/opt/mysql/mysql.sock
!includedir /etc/my.cnf.d

创建MySQL的用户和组，及授权

一般情况下，数据目录会额外使用一个单独的磁盘。

useradd mysql -s /sbin/nologin
chown -R mysql:mysql /opt/mysql
chown -R mysql:mysql /data/mysql

使用systemd的方式管理MySQL

vi /etc/systemd/system/mysqld.service
[Unit]
Description=MySQL Server
Documentation=man:mysqld(5)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/opt/mysql/bin/mysqld --defaults-file=/etc/my.cnf
LimitNOFILE = 5000

或者service mysqld * 这种也可以

cp /opt/mysql/support-files/mysql.server /etc/init.d/mysqld

任选其一

启动方式(c6)：service mysqld start  调用mysqld_safe  调用mysqld；
启动方式(c7)：systemctl start mysqld 调用了mysqld；两者均需依赖my.cnf配置文件。
启动方式：用于日常维护，或者参数测试：可以直接调用mysqld_safe –skip-grant-tables –skip-networking &  其后面可以直接添加参数。同时也会读取my.cnf 但若有冲突，则以命令行为优先.关闭方式：mysqladmin -uroot -p123qwe shutdown

初始化数据库 ```yaml yum install -y libaio-devel 安装依赖 mysqld —initialize —user=mysql —basedir=/opt/mysql —datadir=/data/mysql 2019-04-18T03:21:53.381108Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use —explicit_defaults_for_timestamp server option (see documentation for more details). 2019-04-18T03:21:54.583415Z 0 [Warning] InnoDB: New log files created, LSN=45790 2019-04-18T03:21:54.697859Z 0 [Warning] InnoDB: Creating foreign key constraint system tables. 2019-04-18T03:21:54.760821Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 1daa0c57-6189-11e9-bc80-000c294234c8. 2019-04-18T03:21:54.770856Z 0 [Warning] Gtid table is not ready to be used. Table ‘mysql.gtid_executed’ cannot be opened. 2019-04-18T03:21:54.772016Z 1 [Note] A temporary password is generated for root@localhost: 9LN.fh_Ea#uU #这个为默认生成的root密码并且会往日志中记一份密码过期时间180天

```yaml
mysqld --initialize-insecure  --user=mysql --basedir=/opt/mysql --datadir=/data/mysql
2022-03-23T15:18:04.959891Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2022-03-23T15:18:05.098165Z 0 [Warning] InnoDB: New log files created, LSN=45790
2022-03-23T15:18:05.127039Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2022-03-23T15:18:05.200248Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 700b4272-aabc-11ec-b63f-000c295decd0.
2022-03-23T15:18:05.200845Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2022-03-23T15:18:05.207350Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
默认不生成密码.本次会使用这个方式。

编译安装的方式，参考这个博客

https://blog.51cto.com/u_14834890/2534520

4. 密码设置

当前使用的是无密码的数据库模式。且只能在本地进行登录

MySQL [(none)]>select user,host from mysql.user;  另外两个用户，属于mysql的系统用户，无法登录
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
+---------------+-----------+
3 rows in set (0.00 sec)

[root@localhost support-files]# mysqladmin -uroot -p password
Enter password: 
New password: 
Confirm new password: 
Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.
注释
Enter password:   #输入数据库的当前密码，为空 则直接回车
New password:     #输入新的密码
Confirm new password:   #再次输入密码

5. 破解密码

先关闭数据库

mysqld_safe --skip-grant-tables --skip-networking &
--skip-grant-tables 跳过授权表
--skip-networkin 关闭远程登录

也可以将这两个参数放在数据库配置文件内， 但不太方便。毕竟是临时的操作方式



]# mysqld_safe --skip-grant-tables --skip-networking &
[1] 19804
[root@localhost support-files]# 2022-03-23T15:43:16.245588Z mysqld_safe Logging to '/data/mysql/mysql.log'.
2022-03-23T15:43:16.266911Z mysqld_safe Starting mysqld daemon with databases from /data/mysql

[root@localhost support-files]# 
此时就可以直接登录了。

用户的密码信息以加密的形式，存储在authentication_string 这个字段下。

MySQL [(none)]>select user,host,authentication_string from mysql.user;
+---------------+-----------+-------------------------------------------+
| user          | host      | authentication_string                     |
+---------------+-----------+-------------------------------------------+
| root          | localhost | *050376F3855A67F5E2C6514FD3130B31006C1276 |
| mysql.session | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| mysql.sys     | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+---------------+-----------+-------------------------------------------+
3 rows in set (0.00 sec)

修改密码

手动加载授权表,使用grant命令更改密码

flush privileges;
grant all on *.* to root@'localhost' identified by     '123';
或者
alter user  root@'localhost' identified by '123';

修改完成后，再次查看authentication_string 字段，会发现其发生了变化

MySQL [(none)]>select user,host,authentication_string from mysql.user;
+---------------+-----------+-------------------------------------------+
| user          | host      | authentication_string                     |
+---------------+-----------+-------------------------------------------+
| root          | localhost | *23AE809DDACAF96AF0FD78ED04B6A265E05AA257 |
| mysql.session | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
| mysql.sys     | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+---------------+-----------+-------------------------------------------+
3 rows in set (0.00 sec)

此时输入 exit 或者按ctrl +d 退出数据库
重启数据库。即可按照更改后的密码进入数据库

[root@localhost support-files]# mysql -uroot -p
Enter password:  #此处输入密码

MySQL的安装

1. 常见的数据库类型

2. MySQL选型

3. 安装

4. 密码设置

5. 破解密码