select TRUNC(SYSDATE, 'dd') + (rownum - 1) / 24
  from dual
connect by rownum <= 24;

select to_char(sysdate + (rownum - 1) / 24, 'hh24')
  from dual
connect by rownum <= 24;

5, 获取每年的月份

--本周

select trunc(sysdate, 'd') + 1 from dual;

select trunc(sysdate, 'd') + 7 from dual;

--本月

select trunc(sysdate, 'mm') from dual;

select last_day(trunc(sysdate)) from dual;

--本季

select trunc(sysdate, 'Q') from dual;

select add_months(trunc(sysdate, 'Q'), 3) - 1 from dual;

--本年

select trunc(sysdate, 'yyyy') from dual;

select add_months(trunc(sysdate, 'yyyy'), 12) - 1 from dual;

-- 获取上月的开始时间和结束时间

select to_char(to_date(to_char(add_months(sysdate, -1), 'yyyy-mm'),'yyyy-mm'),'yyyy-mm-dd hh24:mi:ss')

  from dual;

select to_char(to_date(to_char(sysdate, 'yyyy-mm'), 'yyyy-mm'),'yyyy-mm-dd hh24:mi:ss')

  from dual;

-- 获取前一天的开始时间和结束时间

select to_char(to_date(to_char(sysdate - 1, 'yyyy-mm-dd'), 'yyyy-mm-dd'),'yyyy-mm-dd hh24:mi:ss')

  from dual;

select to_char(to_date(to_char(sysdate, 'yyyy-mm-dd'), 'yyyy-mm-dd'),'yyyy-mm-dd hh24:mi:ss')

  from dual;

-- 获取上一个小时的开始时间和结束时间

select to_date(to_char(sysdate, 'yyyy-mm-dd') || (to_char(sysdate, 'hh24') - 1),'yyyy-mm-dd hh24')

  from dual;

select to_date(to_char(sysdate, 'yyyy-mm-dd') || (to_char(sysdate, 'hh24')),'yyyy-mm-dd hh24')

  from dual;