MySQL5.6.6版本之后增加了密码强度验证插件validate_password，相关参数设置的较为严格。使用了该插件会检查设置的密码是否符合当前设置的强度规则，若不满足则拒绝设置。

本文采用测试环境：MySQL 8.0.15

1、在 MySQL安装目录中，\MySQL Server 8.0\lib\plugin 可以看到默认存在validate_password.dll

2、在MySQL 8.0.15中默认没有安装这个插件，我们可以通过  SELECT * from mysql.`plugin` 查看，列表为空。

安装插件：

添加：
　　mysql> INSTALL PLUGIN validate_password SONAME 'validate_password.dll';

卸载：
　　mysql> UNINSTALL PLUGIN validate_password；

插件安装后，使用 show plugins; 查看是否启用成功

3、查看默认策略配置：

show variables like 'validate_password%'; 

4、测试

修改密码

alter user 'root'@'localhost' identified by '';

提示错误

[SQL]alter user 'root'@'localhost' identified by '';

[Err]  - Your password does not satisfy the current policy requirements

各项值说明

validate_password_policy：密码安全策略，默认MEDIUM策略

validate_password_dictionary_file：密码策略文件，策略为STRONG才需要

validate_password_length：密码最少长度

validate_password_mixed_case_count：大小写字符长度，至少1个

validate_password_number_count ：数字至少1个  validate_password_special_char_count：特殊字符至少1个

修改策略（将策略要求置为LOW，长度要求置为1）

set global validate_password_policy=0;
set global validate_password_length=1;

经测试，最小长度为4，设置为1无效，不晓得为什么，后面再查询下。

如不需要，可关闭复杂性策略:

mysql> set global validate_password_policy=;       # 关闭密码复杂性策略

mysql> set global validate_password_length=;      # 设置密码复杂性要求密码最低长度为1

mysql> select @@validate_password_policy;          # 查看密码复杂性策略

mysql> select @@validate_password_length;          # 查看密码复杂性要求密码最低长度大小

重置密码验证，可成功修改：

alter user 'root'@'localhost' identified by '1234';

aaarticlea/png;base64,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" alt="" />

密码重置成功，可重新登录。

参考链接：

https://www.cnblogs.com/zhi-leaf/p/5994478.html