1.创建用户user1、user2和user3,user1具有CREATEROLE权限,user2具有CREATEDB权限,要求使用两种不同的方法设置密码omm=# create user user1 createrole password 'adcd@123';NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.CREATE ROLEomm=# create user user2 createdb identified by...