Find conflicted date intervals using SQL

Question

Suppose I have following table in Sql Server 2008:

ItemId StartDate   EndDate
1      NULL        2011-01-15
2      2011-01-16  2011-01-25
3      2011-01-26           


        

Answer 1

Something like this should give you all overlaping periods

SELECT
* 
FROM
mytable t1 
JOIN mytable t2 ON t1.EndDate>t2.StartDate AND t1.StartDate < t2.StartDate 

Edited for Adrians comment bellow