select  extract(HOUR FROM TIMESTAMP '2010-10-10 9:10:10') as 小时,
extract(MINUTE FROM TIMESTAMP '2010-10-10 9:10:10') as 分钟 ,
ceil((extract(HOUR FROM TIMESTAMP '2010-10-10 9:10:10')*60+extract(MINUTE FROM TIMESTAMP '2010-10-10 9:10:10'))/15) as 节点 
from dual;

------解决方案--------------------

SQL code

select to_char(sysdate, 'yyyymmdd hh24:mi:ss') dt,BASE_TAB.node
from (
select 
to_char(trunc(sysdate) + interval '15' minute * (level - 1),'hh24mi') bt,
to_char(trunc(sysdate) + interval '15' minute * (level) - interval '1' minute,'hh24mi') et,
level node
from dual
connect by level <= 96
) base_tab, dual
where to_char(sysdate, 'hh24mi') between base_tab.bt and base_tab.et

DT                              NODE
------------------------- ----------
20100603 15:12:39                 61

------解决方案--------------------

select sysdate,trunc(sysdate,'hh')+floor(to_char(sysdate,'mi')/15)*15/60/24 from dual;

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2010-6-3 19:54:34	2010-6-3 19:45:00