sql -- 二、删除用户 DROP USER testuser;

-- 四、授权用户访问 GRANT SELECT, INSERT, UPDATE, DELETE ON testdb.testtable TO testuser;

-- 三、修改用户密码 ALTER USER testuser IDENTIFIED BY 'newtestpwd';

-- 创建一个新鲜用户 CREATE USER testuser IDENTIFIED BY 'testpwd';