Execute the following script in Query Editor to unpivot the StartDate and EndDate columns. Column types must be same for the UNPIVOT operator.

USE tempdb;

-- create a table for testing

select ID='I'+convert(varchar,BusinessEntityID)+'D'

             +convert(varchar,DepartmentID),

StartDate, EndDate

into EmployeeDept

from AdventureWorks2008.HumanResources.EmployeeDepartmentHistory

where EndDate is not null

go

--Unpivot the table.

SELECT *

FROM

   (SELECT ID, StartDate, EndDate

   FROM EmployeeDept) p

UNPIVOT

   (Date FOR DateType IN

      (StartDate, EndDate)

)AS unpvt;

GO