Overlapping Date Ranges - Identifying Only the Overlap

Question

I\'ve seen a lot of solutions to identify records where date ranges overlap, and still other examples of merging overlapping ranges.

However I am interested in results

Answer 1

Try:

select ab.CustomerID, 
       case when ab_Eff_Dt > c.Eff_Dt then ab_Eff_Dt else c.Eff_Dt end abc_Eff_Dt,
       case when ab_End_Dt < c.End_Dt then ab_End_Dt else c.End_Dt end abc_End_Dt
from
(select a.CustomerID, 
        case when a.Eff_Dt > b.Eff_Dt then a.Eff_Dt else b.Eff_Dt end ab_Eff_Dt,
        case when a.End_Dt < b.End_Dt then a.End_Dt else b.End_Dt end ab_End_Dt
 from #tmp a
 join #tmp b 
   on a.CustomerID = b.CustomerID and a.Eff_Dt < b.End_Dt and b.Eff_Dt < a.End_Dt
 where a.ProductID = 'PRODUCT_A' and b.ProductID = 'PRODUCT_B') ab
join #tmp c 
  on ab.CustomerID = c.CustomerID and ab_Eff_Dt < c.End_Dt and c.Eff_Dt < ab_End_Dt
where c.ProductID = 'PRODUCT_C' 

(SQLFiddle here)