Question

I have a table called Addim and the data looks like:

TName           Idate        Number
Integrated      3/21/2012    26984013
Integrated      3/20/2012    26959226
Integrated      3/19/2012    26933190

I want the output as:

Idate        Diff
3/21/2012    24787
3/20/2012    26036

I did something like this:

Select Count(*),Idate
from dbo.Addim
group by Idate

But i am getting output like this:

Idate        Diff
03/21/2012   1
03/20/2012   1

basically what it does is it takes the difference from previous day
for example:
for 3/21/2012 the diff is 26984013(3/21/2012)-26959226(3/20/2012) = 24787
and for
3/20/2012 is 26959226(3/20/2012)-26933190(3/19/2012) = 26036

Answer 1

the trick is to join the table back to itself for the previous day, like this:

DECLARE @Addim table (TName varchar(10), Idate datetime,Number int)
INSERT INTO @Addim VALUES ('Integrated','3/21/2012',26984013)
INSERT INTO @Addim VALUES ('Integrated','3/20/2012',26959226)
INSERT INTO @Addim VALUES ('Integrated','3/19/2012',26933190)


SELECT
    a.TName,a.Idate, a.Number-b.Number
    FROM @Addim             a
        INNER JOIN @Addim   b ON a.TName=b.TName AND a.Idate=b.Idate+1

OUTPUT:

TName      Idate                   
---------- ----------------------- -----------
Integrated 2012-03-21 00:00:00.000 24787
Integrated 2012-03-20 00:00:00.000 26036

(2 row(s) affected)

I wasn’t sure the significance of TName, so I joined on that column too, assuming that you’d have multiple different values there as well. You can easily remove it from the join if it is not used like that.