MySQL 5.7 How to Modify an root Password

Beginning with MySQL 5.7, many security updates have been added. Old version of the user may have a bit of unaccustomed, here about the 5.7 version of the database password issues.

Versions after 5.7. 6

Versions after 5.7. 6 generate passwords and put them in the log file when starting the database, like this:

[root@centos-linux ~]# cat /var/log/mysqld.log | grep 'password'
2016-07-16T03:07:53.587995Z 1 [Note] A temporary password is generated for root@localhost: 2=s6NZk.t:fz

Then use the password to log in to the database, but you can't do anything, prompting you to change the password first.

mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

If you change the password here, you will encounter verification, and a simple password will prompt that it does not conform to the rules

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

Because 5.7 introduced an validate_password plug-in to check password strength.

The default values are as follows:

mysql> show variables like 'vali%';
+--------------------------------------+--------+
| Variable_name            | Value |
+--------------------------------------+--------+
| validate_password_dictionary_file  |    | 
| validate_password_length       | 8   | 
| validate_password_mixed_case_count  | 1   |
| validate_password_number_count    | 1   |
| validate_password_policy       | MEDIUM |
| validate_password_special_char_count | 1   |
+--------------------------------------+--------+
6 rows in set (0.01 sec)

The meaning is as follows:

validate_password_length
#  The minimum length of the password, which defaults to 8 . 
validate_password_mixed_case_count
#  Include at least the number of lowercase or uppercase letters, and the default is 1 . 
validate_password_number_count
#  The minimum number of numbers to include, the default is 1 . 
validate_password_policy 
#  Strength level, which can be set to 0 , 1 , 2 . 
   " 0/LOW ": Check length only. 
   " 1/MEDIUM ": In 0 Check numbers, case and special characters based on grades. 
   " 2/STRONG ": In 1 Check the special character dictionary file based on the level, here is 1 . 
validate_password_special_char_count
#  The minimum number of special characters to include, the default is 1 . 

Therefore, the initial password is larger than 8 digits, including numbers, upper and lower case letters and special characters.

At the same time, these configurations can be modified to weaken password strength verification.