Question

I am trying to figure out if any dates in a table for a particular ID overlap. Here is an example of my table

ID   |  EffDate    | ExpDate
---------------------------------
1    |  2000-01-01 | 2010-12-31
2    |  2000-01-01 | 2050-12-31
1    |  2011-01-01 | 2011-12-31
1    |  2011-12-31 | 2050-12-31

In TableA I need to check to make sure that none of the ID’s intersect with “themselves” so none of the 1’s can intersect with any other one but doesn’t matter if the eff and exp dates intersect with ID 2.

Not looking for a complete answer just a starting point.

Thanks in advance

Answer 1

This finds an overlap between two of your rows with ID equal to 1:

declare @TabA table (ID int,EffDate datetime2,ExpDate datetime2)
insert into @TabA(ID,EffDate,ExpDate) values
(1,'20000101','20101231'),
(2,'20000101','20501231'),
(1,'20110101','20111231'),
(1,'20111231','20501231')

select
    * --TODO -Pick columns
from
    @TabA t1
        inner join
    @TabA t2
        on
            t1.ID = t2.ID and
            t1.EffDate <= t2.ExpDate and --Play with these
            t1.ExpDate >= t2.EffDate and --For Inclusive/Exclusive
            t1.EffDate < t2.EffDate

Result:

ID          EffDate                ExpDate                ID          EffDate                ExpDate
----------- ---------------------- ---------------------- ----------- ---------------------- ----------------------
1           2011-01-01 00:00:00.00 2011-12-31 00:00:00.00 1           2011-12-31 00:00:00.00 2050-12-31 00:00:00.00

You can play with the comparison operators to make either or both of EffDate and ExpDate inclusive or exclusive boundary values.