Question

我试图在之前行的窗口上获取最大日期。值得注意的是日期的实际时间部分。

实际表包含更多日期的数据，但查询驻留在一个函数中，该函数将日期作为参数将数据限制为一天。

+---------------------------------------------------------------------+
¦FROM  ¦ TO    ¦ GRAPH                                                ¦
+------+-------+------------------------------------------------------¦
¦09:00 ¦ 11:00 ¦  [--------]                                          ¦
¦10:00 ¦ 10:30 ¦     [-]                                              ¦
¦10:45 ¦ 12:00 ¦         [-------]                                    ¦
¦13:00 ¦ 14:30 ¦                      [--------]                      ¦
¦14:00 ¦ 15:00 ¦                            [-----]                   ¦
¦15:30 ¦ 16:30 ¦                                      [----]          ¦
¦16:30 ¦ 17:30 ¦                                           [-----]    ¦
+---------------------------------------------------------------------+

-- show the time portion when querying, for convenience
alter session set nls_date_format = 'DD/MM/YYYY HH24:MI';

-- create an inline view with some data, perform select on it
with iv_dates (start_dt, end_dt) as ( 
select to_date('08/07/2016 09:00','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 11:00','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 10:00','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 10:30','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 10:30','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 12:00','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 13:00','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 14:30','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 14:00','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 15:00','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 15:30','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 16:30','DD/MM/YYYY HH24:MI') from dual 
union all 
select to_date('08/07/2016 16:30','DD/MM/YYYY HH24:MI'), to_date('08/07/2016 17:30','DD/MM/YYYY HH24:MI') from dual 
) 
 SELECT start_dt 
      , end_dt 
      , MAX (end_dt) OVER ( ORDER BY start_dt asc 
                            RANGE BETWEEN UNBOUNDED PRECEDING 
                            AND     1     PRECEDING 
                          )  
                          max_end_dt
 FROM iv_dates;

但是，我没有得到max end_dt ...

的任何结果

+--------------------------------------------------+
¦ START_DT         ¦ END_DT           ¦ MAX_END_DT ¦
+------------------+------------------+------------¦
¦ 08/07/2016 09:00 ¦ 08/07/2016 11:00 ¦ -          ¦
¦ 08/07/2016 10:00 ¦ 08/07/2016 10:30 ¦ -          ¦
¦ 08/07/2016 10:30 ¦ 08/07/2016 12:00 ¦ -          ¦
¦ 08/07/2016 13:00 ¦ 08/07/2016 14:30 ¦ -          ¦
¦ 08/07/2016 14:00 ¦ 08/07/2016 15:00 ¦ -          ¦
¦ 08/07/2016 15:30 ¦ 08/07/2016 16:30 ¦ -          ¦
¦ 08/07/2016 16:30 ¦ 08/07/2016 17:30 ¦ -          ¦
+--------------------------------------------------+

虽然我每隔一天添加一个日期，但它会开始＆＃34;工作＆＃34;

+--------------------------------------------------------+
¦ START_DT         ¦ END_DT           ¦ MAX_END_DT       ¦
+------------------+------------------+------------------¦
¦ 08/07/2016 09:00 ¦ 08/07/2016 11:00 ¦ -                ¦
¦ 08/07/2016 10:00 ¦ 08/07/2016 10:30 ¦ -                ¦
¦ 08/07/2016 10:30 ¦ 08/07/2016 12:00 ¦ -                ¦
¦ 08/07/2016 13:00 ¦ 08/07/2016 14:30 ¦ -                ¦
¦ 08/07/2016 14:00 ¦ 08/07/2016 15:00 ¦ -                ¦
¦ 08/07/2016 15:30 ¦ 08/07/2016 16:30 ¦ -                ¦
¦ 08/07/2016 16:30 ¦ 08/07/2016 17:30 ¦ -                ¦
¦ 09/07/2016 09:00 ¦ 09/07/2016 11:00 ¦ 08/07/2016 11:00 ¦
¦ 09/07/2016 10:00 ¦ 09/07/2016 10:30 ¦ 08/07/2016 11:00 ¦
¦ 09/07/2016 10:30 ¦ 09/07/2016 12:00 ¦ 08/07/2016 12:00 ¦
+--------------------------------------------------------+

只是为了说明这一点 - 我不需要分区，我只想让它在我的数据上工作一天。

但由于日期数据类型，似乎窗口子句的行为有所不同。我不想要那个 - 我只是希望它根据排序而不是(date - 1)在前一行上工作。是因为这是一个约会，我怎么能处理这个？

Answer 1

如果您使用ORDER BY start_dt asc range BETWEEN UNBOUNDED PRECEDING 1 PRECEDING Oracle计算当前行的逻辑偏移量。例。对于示例中的第一行，范围为08/07/2016 09:00和07/07/2016 09:00 因为（start_dt - 1）= 08/07/2016 09:00 -1 = 07/07/2016 09:00。。将范围更改为行

MAX分析功能，日期窗口保留时间

1 个答案: