操作service表，查询每台unix服务器每天开通的帐号数，查询结果中显示unix服务器ip地址，开通时间，开通的os帐号数，下列sql语句正确的是：( )
select unix_host, to_char(create_date,'yyyymmdd') create_date, count(os_username) cnt
from service
group by unix_host,to_char(create_date,'yyyymmdd');
select unix_host, to_char(create_date,'yyyymmdd') create_date, count(os_username) cnt
from service
group by to_char(create_date,'yyyymmdd');
select unix_host, to_char(create_date,'yyyymmdd') create_date, count(os_username) cnt
from service
group by unix_host;
select unix_host, to_char(create_date,'yyyymmdd') create_date, count(os_username) cnt
from service；
