1.yum 安装后先跑一下系统自带的安全脚本，否则数据库很不安全，任何人都可以登录

[root@xixi ~]# mysql_secure_installation

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user. If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

#输入root的密码，如果没有root密码直接回车就可以

Enter current password for root (enter for none):

OK, successfully used password, moving on…

Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.

#设置root的密码

Set root password? [Y/n]y

New password:
Re-enter new password:
Password updated successfully!
Reloading privilege tables..
… Success!

#到此处数据库的root账号密码设置完成。

By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them. This is intended only for testing, and to make the installation
go a bit smoother. You should remove them before moving into a
production environment.

#删除匿名账号

Remove anonymous users? [Y/n]y

Normally, root should only be allowed to connect from 'localhost'. This
ensures that someone cannot guess at the root password from the network.

#是否禁用root账号远程登陆

Disallow root login remotely? [Y/n]n

By default, MariaDB comes with a database named 'test' that anyone can
access. This is also intended only for testing, and should be removed
before moving into a production environment.

#是否删除测试数据路和数据

Remove test database and access to it? [Y/n]y

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

#重新加载特权表(是否使以上配置生效)

Reload privilege tables now? [Y/n]y

Cleaning up…

All done! If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!

#数据库的安全配置完成

2.[root@xixi ~]# mysql -uroot -p  #mysql -uroot -p123456 也可以登录 但是不安全
Enter password:

用此样式登录数据库，不要-p直接加密码，不安全

3.MariaDB [(none)]> select user();#查看登录的用户

4.默认端口3306