如何从单个日期列-oracle 获取开始/结束日期答案

【问题标题】：How to get start/end date from single date column -oracle如何从单个日期列-oracle 获取开始/结束日期
【发布时间】：2013-07-25 20:22:46
【问题描述】：

我在这里看到了一些出色的答案，我需要修复。我还不想创建表或 ETL，我希望创建一个简单的数据库视图，用户可以先访问以进行测试。

一个表有一个 item#、item_ticket_color#、maint_date 和其他列 tick_col 有时会更新但表中的其他列也是如此。如果其他列被更新或更改 tick_col 迭代。我需要过滤这些数据以获得以下预期结果并需要一些帮助试图弄清楚我该怎么做。如果可能的话，我正在寻找直接的 SQL

ITEM......................TICK_COL................. MAINT_DATE

21524804....................RIBG...................1/1/0001  
21524804....................RIBG...................6/15/2008 6:52:57 AM
21524804....................RIBG...................6/25/2008 11:31:03 AM
21524804....................RIBG...................6/28/2008 4:12:21 AM
21524804....................RIWH...................9/20/2008 6:36:24 AM
21524804....................RIGR...................9/23/2008 6:36:44 AM
21524804....................RIGR...................9/30/2008 6:37:42 AM
21524804....................RIWH...................10/31/2008 6:37:27 AM
21524804....................RIWH...................11/1/2008 6:36:41 AM
21524804....................RIGR...................3/11/2009 6:01:43 PM
21524804....................RIGR...................7/28/2009 6:37:11 AM
21524804....................RIGR...................10/8/2009 6:37:00 AM
21524804....................RIBS...................11/20/2009 6:37:58 AM
21524804....................RIBS...................5/18/2010 6:37:07 AM
21524804....................RIBS...................9/16/2010 6:38:11 AM
21524804....................RIBS...................8/13/2012 10:39:44 AM
21524804....................RIBS...................3/12/2013 6:46:08 AM
21524804....................RIBS...................3/17/2013 9:25:31 AM
21524804....................RIBS...................3/27/2013 6:52:57 AM
21524804....................RIBS...................7/25/2013 6:41:51 AM

我期待在下面看到这个，它显示了开始以及票证颜色发生变化的每个场景的结束日期。：

21524804.....RIBG.....10101........20080919

21524804.....RIWH.....20080920.....20080922

21524804.....RIGR.....20080923.....20081030

21524804.....RIWH.....20081031.....20090310

21524804.....RIGR.....20090311.....20091119

21524804.....RIBS.....20091120.....20130725

SQLFiddle here.

这是新代码，基于 Jasti 的贡献，我做了一些额外的更改，但这正是我想要的

 SELECT item,
       tick_col,
       from_dt,
       CASE
          WHEN LEAD (from_dt) OVER (PARTITION BY item ORDER BY from_dt) - 1
                  IS NULL
          THEN
             SYSDATE
          ELSE
             LEAD (from_dt) OVER (PARTITION BY item ORDER BY from_dt) - 1
       END
          TO_DATE
  FROM (  SELECT ITEM,
                 TICK_COL,
                 MIN (MAINT_DATE) AS from_dt,
                 MAX (MAINT_DATE) AS to_dt
            FROM (SELECT SUM (start_of_group) OVER (ORDER BY maint_date) AS sm,
                         ITEM,
                         TICK_COL,
                         maint_date
                    FROM (SELECT ITEM,
                                 TICK_COL,
                                 maint_date,
                                 CASE
                                    WHEN LAG (TICK_COL, 1, TICK_COL)
                                            OVER (ORDER BY maint_date) =
                                            TICK_COL
                                    THEN
                                       0
                                    ELSE
                                       1
                                 END
                                    start_of_group
                            FROM mytable))
        GROUP BY ITEM, TICK_COL, sm
        ORDER BY sm)

【问题讨论】：

我添加了解决方案并更新了 SQL Fiddle 链接。如果这对您不起作用，请发表评论。
感谢 Jasti，绝对精彩，我必须在其中添加一些东西才能得到我想要的东西，但它确实有效
将解决方案发布为答案并以这种方式标记。不要用解决方案更新问题，因为它应该是问题
@CM 您的解决方案返回最后日期的July, 26，而不是July, 25，如来自问题的示例数据集。 (SQLFiddle)
我的解决方案，可能不是最好的解决方案，我只是做了一些小的调整，但实际上并没有满足我的需求，因为它在数据库视图的上下文中不起作用。

标签： sql oracle lag analytic-functions lead

【解决方案1】：

我也为您的第一部分添加了查询。以下查询应该解决这两个要求。此查询对项目进行分组，直到 TICK_COL 更改并计算该特定组的最大和最小日期

select ITEM, TICK_COL, MIN(MAINT_DATE) AS from_dt, MAX(MAINT_DATE) AS to_dt from
(
  select sum(start_of_group) over (order by maint_date) as sm, ITEM, TICK_COL, maint_date from 
  (
    select  ITEM, TICK_COL,maint_date,
      case
        when 
          lag(TICK_COL,1,TICK_COL) over (order by maint_date)  = TICK_COL then 0
          else 1
         end start_of_group
    from  mytable 
  )
) group by ITEM, TICK_COL,sm order by sm

更新SQL Fiddle here

【讨论】：

我对我的数据进行了 SQL Fiddle，并且我使用了您的查询，开始和结束日期都已关闭，请查看我的预期结果....
@CM - 如果这对你有帮助，那么至少要投赞成票。如果这是答案，请标记为这样。

【解决方案2】：

您可以使用 min 和 max 来获取第二部分。除了标准选择之外，我不确定您在第一部分中要查找的内容。

SELECT ITEM, TICK_COL, MIN(MAINT_DATE) AS startDate, MAX(MAINT_DATE) AS endDate
FROM yourTableName
GROUP BY ITEM, TICK_COL

【讨论】：

【解决方案3】：

试试看这个查询是否有效。

   select item,
           tick_col,
           MAINT_DATE maint_start_date,
           (case when tick_col <> next_tick_col then next_maint_date end) maint_end_date
    from (
      select item,
             tick_col,
             lead(MAINT_DATE) over (partition by item 
                                    order by MAINT_DATE asc) next_maint_date,
             lead(tick_col) over (partition by item 
                                  order by MAINT_DATE asc) next_tick_col,
      from   my_table
) where tick_col <> next_tick_col;

【讨论】：

【解决方案4】：

基于检测期间开始和结束的变体，然后计算所需日期。（可以找到几乎相同的解决方案here。）

SQLFiddle

with marked_set as (
  -- mark start and end of each maintenance period
  select
    item,
    tick_col,
    maint_date,
    decode( nvl(prev_tick, tick_col||'x'), tick_col, 0, 1 ) is_start,
    decode( nvl(next_tick, tick_col||'x'), tick_col, 0, 1 ) is_end
  from (
    select
      item,
      tick_col,
      maint_date,
      lag(tick_col)  over (partition by item order by maint_date) prev_tick,
      lead(tick_col) over (partition by item order by maint_date) next_tick
    from
      mytable
  )
),
boundary_set as (
  -- Leave only start and end of each period
  -- and get dates from previous and next lines
  select
    item,
    tick_col,
    maint_date,
    is_start,
    is_end,
    ( lag(maint_date) over (
        partition by item order by maint_date)
    )                                          prev_maint_date,
    ( lead(maint_date,1,maint_date) over (
        partition by item order by maint_date
      )
    )                                          next_maint_date
  from
    marked_set
  where
    1 in (is_start, is_end)
),
maintenance_sequence as (
  -- Calculate start and end dates for each maintenance period
  select distinct
    item,
    tick_col,
    decode( is_start,
      1, maint_date,
      prev_maint_date
    )                     start_date,
    decode( is_end,
      1, next_maint_date,
      ( lead(next_maint_date,1,next_maint_date)
         over (partition by item order by maint_date)
      )
    )                    end_date
  from
    boundary_set
)
select
  -- Final formatting and ordering.
  -- For end date of last period get exact date, for others get previous date
  -- because it's date of start for maintenance of next item.
  item,
  tick_col,
  to_char(start_date, 'yyyymmdd') maint_start,
  decode( (lead(end_date) over (partition by item order by start_date)),
    null, to_char(end_date, 'yyyymmdd'),
    to_char(end_date - 1, 'yyyymmdd')
  )
   maint_end
from
  maintenance_sequence
order by
  maint_start

【讨论】：