Oracle PLSQL将日期时间截断为15分钟

Question

我想将我的数据汇总到15分钟段(一小时的季度).为此,我编写了一些生成15分钟日期时间块的代码.

SELECT 
   TRUNC(SYSDATE,'hh') + 0.25/24 - (ROWNUM) *0.25/ 24
   AS time_start,
   ROWNUM,
   TRUNC(SYSDATE,'hh') + 0.25/24 - (ROWNUM - 1) *0.25/ 24
   AS time_end
FROM widsys.consist 
WHERE ROWNUM <3000
ORDER BY sysdate

我的代码的问题是因为它使用了一个小时截断,它只会从最近一小时的开始生成时间戳.例如,11:49AM现在生成的第一个戳是11:00AM.

我需要它从最后15分钟的块开始生成标记(11:45AM从上面的例子).谁能帮帮我吗？

Answer 1

这将为您提供最近的季度.

select sysdate,
       trunc(sysdate,'mi') -                           --truncate to the nearest minute
       numtodsinterval(                                --convert the minutes in number to interval type and subtract.
                       mod(to_char(sysdate,'mi'),15),  --find the minutes from the nearest quarter
                      'minute'                          
                      ) as nearest_quarter
  from dual;

输出:

sysdate                             nearest_quarter
-----------------------------------------------------------------
October, 11 2013 05:54:24+0000      October, 11 2013 05:45:00+0000
October, 11 2013 05:22:24+0000      October, 11 2013 05:15:00+0000

使用它作为起始值,然后迭代它.

with cte as(
  select trunc(sysdate,'mi') - 
         numtodsinterval(mod(to_char(sysdate,'mi'),15),'minute') as nearest_quarter
  from dual
  )
select nearest_quarter - numtodsinterval((level - 1)*15, 'minute'),
       nearest_quarter - numtodsinterval((level - 2)*15, 'minute')
from cte
connect by level <= 10;

演示.