安裝mariadb，默認是無密碼的，但一般是指要設置密碼的。在設置密碼時出現各種問題，可能還是不太明白其原理。
一下我嘗試了兩種方法，但都失敗了。下面這兩個是我嘗試的方法：
一、網上最多的方法是
1、輸入下面的指令
mysqladmin -u root -p password newpassword
但是我已輸入提示輸入密碼，我輸入密碼了但提示錯誤，見下
[root@localhost sakila]# mysqladmin -u root -p password newpasswd
Enter password:
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: YES)'
2、停掉數據庫服務
systemctl stop mariadb.service
3、對所有的表設置成無密碼登陸。
mysqld_safe --skip-grant-tables &
執行完這條語句提示一下錯誤
[root@localhost sakila]# mysqld_safe --skip-grant-tables &
[1] 14275
[root@localhost sakila]# 150424 10:13:41 mysqld_safe Logging to '/var/log/mariadb/mariadb.l
og'.150424 10:13:41 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
4、嘗試退出數據庫，然後重啓服務，再進入
[root@localhost sakila]# systemctl restart mariadb.service
[root@localhost sakila]# mysqladmin -u root -p password 'passwd'
Enter password:
mysqladmin:
You cannot use 'password' command as mysqld runs
with grant tables disabled (was started with --skip-grant-tables).
Use: "mysqladmin flush-privileges password '*'" instead
二、正確的操作
1、進到數據庫進行操作
[root@localhost etc]# mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 7
Server version: 5.5.41-MariaDB MariaDB Server
Copyright (c) 2000, 2014, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> mysql
-> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds
to your MariaDB server version for the right syntax to use near 'mysql' at line 1MariaDB [(none)]> update user set password=password("123456")where user='root';
ERROR 1046 (3D000): No database selected
2、選擇數據庫
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
3、用戶root添加密碼
MariaDB [mysql]> update user set password=password("123456")where user='root';
Query OK, 0 rows affected (0.00 sec)
Rows matched: 4 Changed: 0 Warnings: 0
4、賦予權限
MariaDB [mysql]> flush privileges;
Query OK, 0 rows affected (0.00 sec)
5、退出，重新登錄
MariaDB [mysql]> exit
Bye
6、嘗試無密碼是否可以登錄
[root@localhost etc]# mysql
提示錯誤
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
7、輸入密碼登陸
[root@localhost etc]# mysql -u root -p123456
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 9
Server version: 5.5.41-MariaDB MariaDB Server
Copyright (c) 2000, 2014, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]>