Merge two tables and find overlapping dates and Gaps

问题

I would like to solve below scenarios for ID 100 & 101 as given output using oracle Analytical functions. any ideas?

TABLE A:

ID   ValidFrom   ValidTo
100  1/1/2009    12/31/2010
100  1/1/2011    3/31/2012
101  8/1/2013    7/31/2014
101  8/1/2014    8/31/2014

TABLE B

ID   ValidFrom   ValidTo
100  11/1/2008   12/31/2011
100  2/1/2012    2/29/2012
101  8/1/2013    6/30/2014
101  7/1/2014    8/31/2014

OUTPUT:

ID   ValidFrom   ValidTo
100  11/1/2008  12/31/2008
100  1/1/2009   12/31/2010
100  1/1/2011   12/31/2011
100  1/1/2012   1/31/2012
100  2/1/2012   2/29/2012
100  3/1/2012   3/31/2012
---------------------------
101  8/1/2013   6/30/2014
101  7/1/2014   7/31/2014
101  8/1/2014   8/31/2014

回答1:

This query, using analytic lead() does the job. Column note shows if row comes from your data or if it is missing gap:

select id, d1, d2, case dir when 3 then 'GAP' end note 
  from (
    select id, 
           case when dir = 2 
                 and lead(dir) over (partition by id order by dt) = 1
                 and lead(dt) over (partition by id order by dt) <> dt + 1
                then dt + 1 
                else dt
           end d1,
           case when dir = 2 
                 and lead(dir) over (partition by id order by dt) = 1
                 and lead(dt) over (partition by id order by dt) <> dt + 1
                then 3 
                else dir
           end dir,
           case when lead(dir) over (partition by id order by dt) = 1 
                then lead(dt)  over (partition by id order by dt) - 1
                else lead(dt)  over (partition by id order by dt) 
            end d2
      from (
        select * from a unpivot (dt for dir in (validfrom as 1, validto as 2)) union 
        select * from b unpivot (dt for dir in (validfrom as 1, validto as 2)) ) )
  where dir in (1, 3)

^{dbfiddle demo}

At first data is unpivoted just to have all dates in one column, it's easier for further analytics. Union removes duplicated values. Column dir informs if this is from or to date. Then lead logic is applied, depending on type of this direction. I think it can be simplified somewhat :)

来源：https://stackoverflow.com/questions/62498407/merge-two-tables-and-find-overlapping-dates-and-gaps

标签

sql

Oracle

overlapping