获取某段时间内的小时、日期、月份，存储过程中使用的较多。

--月的第一天 20161201

select to_char(last_day(add_months(to_date('2016-12','yyyy-MM'),-1))+1,'yyyy-MM-dd') from dual;

--月最后一天 20161231

select to_char(last_day(to_date('2016-12','yyyy-MM')),'yyyy-MM-dd') from dual;

--月的第一天 2016-12-01 00:00:00

select to_char(last_day(add_months(to_date('2016-12','yyyy-MM'),-1))+1,'yyyy-MM-dd') ||' 00:00:00'  from dual;

--月最后一天 2016-12-31 23:59:59
select to_char(last_day(to_date('2016-12','yyyy-MM')),'yyyy-MM-dd') ||' 23:59:59' from dual;

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--获取一段时间内所有的小时

SELECT to_char(to_date('2013-07-01 00:00:00', 'yyyy-mm-dd hh24:mi:ss') +
(ROWNUM - 1) / 24,
'yyyy-MM-dd hh24:mi:ss') sdate
FROM dual
CONNECT BY ROWNUM <=
(to_date('2013-07-02 23:59:59', 'yyyy-mm-dd hh24:mi:ss') -
to_date('2013-07-01 00:00:00', 'yyyy-mm-dd hh24:mi:ss')) * 24 + 1;

--0-23修改1-24
select sdate+1 from(
SELECT to_char(to_date('2013-07-01 00:00:00', 'yyyy-mm-dd hh24:mi:ss') +(ROWNUM - 1) / 24, 'yyyyMMddhh24') sdate  FROM dual
CONNECT BY ROWNUM <=
(to_date('2013-07-02 23:59:59', 'yyyy-mm-dd hh24:mi:ss') -
to_date('2013-07-01 00:00:00', 'yyyy-mm-dd hh24:mi:ss')) * 24 + 1)

--获取一段时间内所有的天
SELECT to_date('20130701', 'yyyymmdd') + ROWNUM - 1 sdate
FROM dual
CONNECT BY ROWNUM <= to_date('20130705', 'yyyymmdd') -
to_date('20130701', 'yyyymmdd') + 1;

--获取一段时间内所有的月
SELECT to_char(add_months(to_date('201612', 'yyyymm'), ROWNUM - 1),
'yyyymm') day_id
FROM dual
CONNECT BY ROWNUM <=
months_between(to_date('201702', 'yyyymm'),
to_date('201612', 'yyyymm')) + 1;