案例：Mysql数据库报 ERROR 1045 (28000)报错；同时该方法适用于忘记MySQL Password找回；重新安装mysql手动清空mysqld.log日志文件导致初始 Password丢失 Password修改；
案例1：
[root@zrbapp02 lib]#
[root@zrbapp02 lib]# mysql -uroot -pmysql
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user ‘root’@’localhost’ (using password: YES)
[root@zrbapp02 lib]#
[root@zrbapp02 lib]#
案例2：
[root@zrbapp02 ~]# echo “” > /var/log/mysqld.log —-清空mysqld.log日志文件后查不到
[root@zrbapp02 ~]#
[root@zrbapp02 ~]# grep ‘temporary password’ /var/log/mysqld.log –mysqld.log日志文件查不到初始 Password
[root@zrbapp02 ~]#
[root@zrbapp02 ~]#
[root@zrbapp02 ~]# systemctl restart mysqld
[root@zrbapp02 ~]#
解决方法：
1、修改/etc/my.cnf文件中[mysqld]段增加 skip-grant-tables跳过认证
[root@zrbapp02 lib]# vi /etc/my.cnf
#socket=/mysqldb/mysql/mysql.sock
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
[mysqld]
skip-grant-tables
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
#datadir=/var/lib/mysql
datadir=/mysqldb/mysql
socket=/var/lib/mysql/mysql.sock
#socket=/mysqldb/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
wq! —-保存并退出
2、重启mysql数据库
[root@zrbapp02 lib]# systemctl restart mysqld
[root@zrbapp02 lib]#
3、免密登录数据库并修改 Password
[root@zrbapp02 lib]#
[root@zrbapp02 lib]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.25 MySQL Community Server (GPL)
Copyright (c) 2000, 2019, 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> show databases;
+——————–+
| Database |
+——————–+
| information_schema |
| mysql |
| performance_schema |
| sys |
+——————–+
4 rows in set (0.24 sec)
mysql>
mysql> 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
mysql>
mysql>
mysql> update mysql.user set authentication_string=password(‘mysql’) where user=’root’;
Query OK, 1 row affected, 1 warning (0.14 sec)
Rows matched: 1 Changed: 1 Warnings: 1
mysql>
mysql> flush privileges ;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> exit
Bye
[root@zrbapp02 lib]#
[root@zrbapp02 lib]#
4、 注释掉 skip-grant-tables
[root@zrbapp02 lib]# vi /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
[mysqld]
#skip-grant-tables
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
#datadir=/var/lib/mysql
datadir=/mysqldb/mysql
socket=/var/lib/mysql/mysql.sock
#socket=/mysqldb/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
wq! —-保存并退！
5、重启mysql数据库
[root@zrbapp02 lib]# systemctl restart mysqld
[root@zrbapp02 lib]#
6、使用新 Password登录数据库
[root@zrbapp01 ~]#
[root@zrbapp01 ~]# mysql -uroot -pmysql
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: 5.7.25
Copyright (c) 2000, 2019, 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> show databases; –查看数据库时要求使用ALTER USER rest Password
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql>
mysql> alter user’root’@’localhost’ identified by’mysql’; —-重置 Password 提示 Password规则问题，不能使用简单 Password；
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql>
mysql>
若需要设置简单 Password则按以下设置 Password规则即可；
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_mixed_case_count=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_number_count=3;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_special_char_count=0;
Query OK, 0 rows affected (0.01 sec)
mysql> set global validate_password_length=3;
Query OK, 0 rows affected (0.00 sec)
mysql> alter user’root’@’localhost’ identified by’mysql’;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql> show databases;
+——————–+
| Database |
+——————–+
| information_schema |
| mysql |
| performance_schema |
| sys |
+——————–+
4 rows in set (0.00 sec)
mysql>
mysql> 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
mysql>
mysql>
