安装mariadb（mysql）并创建账户
(red hat内置的安装已经是mariadb，而非mysql，因为二者差不多，所以不建议重新下载mysql，建议直接用mariadb)
安装：
[root@localhost ~]# dnf -y install mariadb*
启动：
[root@localhost ~]# systemctl start mariadb
[root@localhost ~]# systemctl status mariadb
[root@localhost ~]# firewall-cmd --permanent --add-service=mysql
[root@localhost ~]# firewall-cmd --reload
[root@localhost ~]# firewall-cmd --permanent --add-service=mariadb
Error: INVALID_SERVICE: mariadb
[root@localhost ~]# mysql_secure_installation
进入root下的mariadb（即mysql）
[root@localhost ~]# mysql -u root -p
Enter password: （这里要输入密码）
Welcome to the MariaDB monitor. Commands end with ; or g.
Your MariaDB connection id is 13
Server version: 10.1.26-MariaDB MariaDB Server
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or 'h' for help. Type 'c' to clear the current input
输入密码后进入
MariaDB [(none)]>
#------
建账户：
MariaDB [(none)]> create database menmydb;
Query OK, 1 row affected (0.02 sec)
创建密码：
MariaDB [(none)]> create user menxiaolei@localhost identified by 'men12xiao34lei56';
Query OK, 0 rows affected (0.02 sec)
给权限：
MariaDB [(none)]> grant all on menmydb.* to menxiaolei@localhost identified by 'men12xiao34lei56';
Query OK, 0 rows affected (0.02 sec)
退出
MariaDB [(none)]>
Ctrl+D
#——————————————————–
普通用户使用menmydb
[xjj@localhost ~]$ mysql -u menxiaolei -p
Enter password: （这里输入密码）
Welcome to the MariaDB monitor. Commands end with ; or g.
Your MariaDB connection id is 17
Server version: 10.1.26-MariaDB MariaDB Server
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| menmydb |
+--------------------+
2 rows in set (0.00 sec)
MariaDB [(none)]> show tables;
MariaDB [(none)]> describe servers;
Ctrl+D