查询service表中服务器地址，服务器OS帐号，登录UNIX服务器口令，下列sql语句正确的是：( )
select unix_host/os_username/login_passwd from service;
select unix_host,os_username from service;
select unix_host and os_username and login_passwd from service;
select unix_host,os_username,login_passwd from service;
