mysql修改用户名和密码

-- 修改密码
ALTER USER 'old_username'@'localhost' IDENTIFIED BY 'new_password';

-- 修改用户名（MySQL 8.0及以上版本）
ALTER USER 'old_username'@'localhost' RENAME TO 'new_username';

-- 修改密码
SET PASSWORD FOR 'old_username'@'localhost' = PASSWORD('new_password');

-- 修改密码
UPDATE mysql.user SET Password = PASSWORD('new_password') WHERE User = 'old_username' AND Host = 'localhost';
FLUSH PRIVILEGES;

-- 使用root用户登录
mysql -u root -p

-- 然后执行修改操作
ALTER USER 'old_username'@'localhost' IDENTIFIED BY 'new_password';

-- 检查用户是否存在
SELECT User, Host FROM mysql.user WHERE User = 'old_username' AND Host = 'localhost';

-- 查看密码策略
SHOW VARIABLES LIKE 'validate_password%';

-- 修改密码策略（示例）
SET GLOBAL validate_password_policy = LOW;