Yep, as Sean said I assumed that you use SQL 2012 and windows offset functions are a good choice in situations where you want to refer to some other row from your row.

Anyway, if you cannot use SQL 2012 the following query is logically equivalent to the query I provided in previous post:

SELECT RowID,

CASE WHEN DATEDIFF(DAY, Date2,

(

SELECT TOP 1 Date1

FROM YourTable t2

WHERE t1.IDNo = t2.IDNo AND t1.RowId < t2.RowId

ORDER BY t2.RowId ASC

)

) < 14

THEN 1

ELSE 0

END IsDateDiffLess14_Calculation

FROM YourTable t1

ORDER BY RowID