Loop with calculation

I have a table which contains numerical data in a field called active_en_del. I need to loop through this table and perform a calculation where row 2 minus row 1 = and store into another field; row 3 - row 2 = and store into another field etc. How would I perform this? Thanks

I am not sure which DB you are using. You also say that you want to store the difference in different "field"s. I am not sure if by fields, you mean columns or what. Using this below approach, you can get all the results in rows:

Assuming sql server 2005, you can get rownumbers for all the rows using row_number() over(order by id)

and then do a self join.

Code Snippet

select a.col1-b.col1 from

(select col1, row_number() over(order by id) as rowid
from tblData)
a,

(select col1, row_number() over(order by id) as rowid
from tblData)

b

where a.rowid=b.rowid+1

|||My appology for not specifying. Yes it is sql 2005 and it a calculation on the same column. Thanks for the above information.sql