调整 mysql policy requirements

Error：

mysql> CREATE USER 'tester'@'%' IDENTIFIED BY 'password';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

解决方法：

mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password.check_user_name    | ON     |
| 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      |
+--------------------------------------+--------+

mysql> SET GLOBAL validate_password.mixed_case_count = 0;
Query OK, 0 rows affected (0.00 sec)

以此类推，所有字段均可调整。