Only select records that do not start within the time frame of another record - sql

Question

I'm trying to achieve the following goal using MS SQL Server 2005 but do not know how to do it.
The goal is to select only records that do not start within the same time period as an anchor record.
Rows that have same ID are a group and evaluated as part of that group.
Start with the earliest date (A) based on StartDate, compare to the next row (B) that has the same ID.
If B starts within A, mark B as invalid. Continue to compare A against all remaining records that have the same ID. Mark any starting within A as invalid.
Flag the next record that does not overlap with A as Valid. Now repeat the same process as above (i.e. check to see if any subsequent records start within the time frame of the new valid record).
Repeat this process until all records have been analyzed.
Example: Create the following table.
if object_id ('tempdb..#Dates') is not null drop table #Dates
create table #Dates (ID int, StartDate datetime, EndDate datetime)
Insert into #Dates
Select 1, '7/23/2003' , '8/22/2003' union all
select 1, '8/21/2003' , '11/19/2003' union all
select 1, '11/18/2003' , '12/18/2003' union all
select 1, '12/17/2003' , '1/16/2004' union all
select 1, '1/15/2004' , '2/14/2004' union all
select 1, '2/11/2004' , '2/26/2004' union all
select 1, '9/14/2004' , '10/14/2004' union all
select 1, '10/5/2004' , '10/20/2004' union all
select 1, '11/20/2004' , '12/20/2004' union all
select 1, '12/19/2004' , '1/18/2005' union all
select 1, '1/12/2005' , '1/27/2005' union all
select 1, '2/27/2005' , '3/11/2005'
Expected output after applying the overlap logic rules:
ID StartDate EndDate Valid
-- --------- --------- -----
1 7/23/2003 8/22/2003 1
1 8/21/2003 11/19/2003 0
1 11/18/2003 12/18/2003 1
1 12/17/2003 1/16/2004 0
1 1/15/2004 2/14/2004 1
1 2/11/2004 2/26/2004 0
1 9/14/2004 10/14/2004 1
1 10/5/2004 10/20/2004 0
1 11/20/2004 12/20/2004 1
1 12/19/2004 1/18/2005 0
1 1/12/2005 1/27/2005 1
1 2/27/2005 3/11/2005 1

Answer 1

I figured out how to answer my own question. Used recursive SQL after ordering the records using row_number.
if object_id ('tempdb..#Dates') is not null drop table #Dates
create table #Dates (ID int, StartDate datetime, EndDate datetime)
Insert into #Dates
Select 1, '7/23/2003' , '8/22/2003' union all
select 1, '8/21/2003' , '11/19/2003' union all
select 1, '11/18/2003' , '12/18/2003' union all
select 1, '12/19/2004' , '1/18/2005' union all
select 1, '1/12/2005' , '1/27/2005' union all
select 1, '2/27/2005' , '3/11/2005' union all
select 1, '12/17/2003' , '1/16/2004' union all
select 1, '1/15/2004' , '2/14/2004' union all
select 1, '2/11/2004' , '2/26/2004' union all
select 1, '9/14/2004' , '10/14/2004' union all
select 1, '10/5/2004' , '10/20/2004' union all
select 1, '11/20/2004' , '12/20/2004'
--Phase 1: Apply ordering to dates
if object_id ('tempdb..#OrderedRecords') is not null drop table #OrderedRecords
select *, N = row_number () over (partition by ID order by StartDate asc, EndDate desc)
into #OrderedRecords
from #Dates
--Phase 2: Apply Overlap Rules (Subsume records that overlap)
;with Subsume (ID, N, StartDate, EndDate, IntermediateStartDate, IntermediateEndDate, Valid) as
(
select ID, N, StartDate, EndDate, IntermediateStartDate = StartDate, IntermediateEndDate = EndDate,
Valid = 1
from #OrderedRecords
where N = 1
UNION ALL
select c.ID, c.N, y.StartDate, y.EndDate,
IntermediateStartDate = case when c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate then y.IntermediateStartDate else c.StartDate end,
IntermediateEndDate = case when c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate then y.IntermediateEndDate else c.EndDate end,
Valid = case when (c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate) then 0 else 1 end
from #OrderedRecords c
join Subsume y
on y.ID = c.ID
and y.N = c.n - 1
and y.IntermediateStartDate >= c.EndDate
UNION ALL
select c.ID, c.N, c.StartDate, c.EndDate,
IntermediateStartDate = case when c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate then y.IntermediateStartDate else c.StartDate end,
IntermediateEndDate = case when c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate then y.IntermediateEndDate else c.EndDate end,
Valid = case when (c.StartDate between y.IntermediateStartDate and y.IntermediateEndDate) then 0 else 1 end
from #OrderedRecords c
join Subsume y
on y.ID = c.ID
and y.N = c.n - 1
and y.IntermediateStartDate < c.EndDate
)
Select ID, StartDate, EndDate, Valid
from Subsume
OPTION (MAXRECURSION 0)