1. 修改資料庫密碼（已知原密碼）

進入shell
mysqladmin -uroot -p原密碼 password 新密碼

root@a038a278a3db:/var/lib/mysql# mysqladmin -u root -proot password 123456
root@a038a278a3db:/var/lib/mysql# 

然後就可以直接使用123456這個密碼登陸了

mysql -u root -p123456

2. 初始化密碼

[root@localhost /]# 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.

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.

Set root password? [Y/n] y ##輸入y
New password: ##輸入密碼
Re-enter new password: ##輸入密碼
Password updated successfully!
Reloading privilege tables..
 ... Success!


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.

Remove anonymous users? [Y/n] y ##輸入y
 ... Success!

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

Disallow root login remotely? [Y/n] y  ##輸入y
 ... Success!

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.

Remove test database and access to it? [Y/n] y  ##輸入y
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

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

Reload privilege tables now? [Y/n] y  ##輸入y
 ... Success!

Cleaning up...

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

Thanks for using MariaDB!
 

進入資料庫

[root@localhost /]# mysql -u root -p
Enter password:  ##輸入密碼
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 12
Server version: 5.5.65-MariaDB MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]>
 

3. 資料庫常規命令

1.啟動資料庫 [root@localhost jdk1.8]# systemctl start mariadb
2.重啟資料庫 [root@localhost jdk1.8]# systemctl restart mariadb
3.關閉資料庫 [root@localhost jdk1.8]# systemctl stop mariadb

4. 開啟遠端訪問許可權

4.1 先檢視資料庫中的訪問許可權

MariaDB [(none)]> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MariaDB [mysql]> select host ,user from user;
+-----------+------+
| host      | user |
+-----------+------+
| 127.0.0.1 | root |
| ::1       | root |
| localhost | root |
+-----------+------+
3 rows in set (0.00 sec)

MariaDB [mysql]>
 

現在root的訪問許可權僅限在本地訪問

4. 2 修改訪問許可權

MariaDB [mysql]> update user set host="%" where host="localhost";
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

MariaDB [mysql]> select host ,user from user;
+-----------+------+
| host      | user |
+-----------+------+
| %         | root |
| 127.0.0.1 | root |
| ::1       | root |
+-----------+------+
3 rows in set (0.00 sec)

4.3 重新整理許可權

MariaDB [mysql]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

MariaDB [mysql]>