Subtracting one row of data from another in SQL

Question

I\'ve been stumped with some SQL where I\'ve got several rows of data, and I want to subtract a row from the previous row and have it repeat all the way down.

So her

Answer 1

Yipee!!! this does the trick:

SELECT  f.id, f.length, 
    (f.length - ISNULL(f2.length,0)) AS diff
FROM foo f
LEFT OUTER JOIN foo f2
ON  f2.id = (f.id +1)

Please check for other cases also, it is working for the values you posted! Note this is for SQL Server 2005