判断当天：

select * from table_name

where v_date>=trunc(sysdate)

获取今天小时列表，两种方法都可以

select level,to_char(trunc(sysdate)+level/24-1,'HH24') as dat
from dual
connect by level <= ROUND(TO_NUMBER(sysdate - trunc(sysdate)) * 24)

select to_char(sysdate +(rownum - 1) / 24,'hh24') AS shijian from DUAL connect by rownum <= 24 ORDER BY shijian