Detailed steps for installing and debugging MySQL database on CentOS7 [Example]

[root@agt20 ~]# ls mysql-*
mysql-5.7.17.tar
mysql-community-client-5.7.17-1.el7.x86_64.rpm
mysql-community-common-5.7.17-1.el7.x86_64.rpm
mysql-community-devel-5.7.17-1.el7.x86_64.rpm
mysql-community-embedded-5.7.17-1.el7.x86_64.rpm
mysql-community-embedded-compat-5.7.17-1.el7.x86_64.rpm
mysql-community-embedded-devel-5.7.17-1.el7.x86_64.rpm
mysql-community-libs-5.7.17-1.el7.x86_64.rpm
mysql-community-libs-compat-5.7.17-1.el7.x86_64.rpm
mysql-community-minimal-debuginfo-5.7.17-1.el7.x86_64.rpm
mysql-community-server-5.7.17-1.el7.x86_64.rpm
mysql-community-test-5.7.17-1.el7.x86_64.rpm

[root@agt20 ~]# yum -y install mysql-*.rpm
[root@agt20 ~]# systemctl restart mysqld
[root@agt20 ~]# systemctl enable mysqld
[root@agt20 ~]# systemctl status mysqld.service 
mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since \u4e8c 2019-10-15 11:29:11 CST; 1min 15s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Main PID: 31584 (mysqld)
CGroup: /system.slice/mysqld.service
\u2514\u250031584 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid...

10\u6708 15 11:28:42 agt20.tedu.cn systemd[1]: Starting MySQL Server...
10\u6708 15 11:29:11 agt20.tedu.cn systemd[1]: Started MySQL Server.
[root@agt20 ~]#

[root@agt20 ~]# grep -i 'password' /var/log/mysqld.log 
2019-10-15T03:28:55.200931Z 1 [Note] A temporary password is generated for root@localhost: r3qhDysMrM)

[root@agt20 ~]# mysql -uroot -p'r3qhDysMrM)'
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: 5.7.17
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
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>

mysql> alter user root@localhost identified by 'Pwd@123...';
Query OK, 0 rows affected (0.00 sec)

mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.01 sec)
mysql> set global validate_password_length=6;
Query OK, 0 rows affected (0.00 sec)
mysql> alter user root@localhost identified by 'pwd@123';
Query OK, 0 rows affected (0.00 sec)

[root@agt20 ~]# mysql -uroot -ppwd@123
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 5
Server version: 5.7.17 MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
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>