Help with a SQL Query - sql

Question

I am wanting to perform a Threshold query, whereby one would take the Value of a field from Today, and compare it to the value from yesterday, this query would look something like this, but obviously, it is wrong, and I can't find how to do it:
select
TableB.Name,
TableA.Charge,
(
select Charge
from TableA
where (DateAdded >= '13/10/2009' and DateAdded < '14/10/2009')
)
from TableA
inner join
TableB on TableB.ID = TableA.ID
where
TableA.DateAdded >= '10/14/2009'
order by
Name asc
Just a quick note, I am looking for two CHARGE fields, not the dates. The date manipulation is simply for Today and Yesterday, nothing more.
At the end of this, I want to do a calculation on the two returned charge fields, so if its easier to show that, that would also be great.
Thanks in advance
Kyle
EDIT1:
The data I am looking for is like so:
Yesterday, we input a charge of 500 to MachineA
Today we input a charge of 300 to MachineA
We run the query, and results I need are as follows:
Name = MachineA
Charge = 300
YesterdayCharge = 500

Answer 1

If you really need previous date (including weekends etc), then following query should do the job. Otherwise please post data samples and expected results:
SELECT TableB.Name,
TableA.Charge,
prev.Charge AS PrevCharge
FROM TableA
INNER JOIN TableB
ON TableA.ID = TableB.ID
LEFT JOIN TableA prev
ON TableA.ID = prev.ID
--// use this if DateAdded contains only date
--AND TableA.DateAdded = DATEADD(day, +1, prev.dateAdded)
--// use this if DateAdded contains also time component
AND CONVERT(DATETIME, CONVERT(CHAR(8), TableA.DateAdded, 112), 112) = DATEADD(day, +1, CONVERT(DATETIME, CONVERT(CHAR(8), prev.dateAdded, 112), 112))
edit-1: added option in JOIN for cases when DateAdded contains time as well

Answer 2

something like this?
SELECT
B.Name,
A.Charge,
DATEPART(day, A.DateAdded) as day
FROM
TableA A, Table B
WHERE
B.ID = A.ID AND
A.DateAdded BETWEEN DATEADD(day, -1, GETDATE()) AND GETDATE()
GROUP BY
B.Name,
A.Charge,
A.DateAdded

Answer 3

Try this:
DECLARE #ValuesTable TABLE(Name VARCHAR(20), Charge INT, DateAdded DATETIME)
INSERT INTO #ValuesTable
SELECT 'Name1', 10, DATEADD(dd, 2, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name2', 20, DATEADD(dd, 2, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name1', 30, DATEADD(dd, 1, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name2', 40, DATEADD(dd, 1, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name1', 50, DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name2', 60, DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name1', 70, DATEADD(dd, -1, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name3', 80, DATEADD(dd, -1, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name1', 90, DATEADD(dd, -2, DATEDIFF(dd, 0, GETDATE())) UNION
SELECT 'Name2', 100, DATEADD(dd, -2, DATEDIFF(dd, 0, GETDATE()))
SELECT
ISNULL(T.Name,Y.Name) AS Name,
SUM(ISNULL(Y.Charge,0)) AS Yesterday, SUM(ISNULL(T.Charge,0)) AS Today,
SUM(ISNULL(T.Charge,0)) - SUM(ISNULL(Y.Charge,0)) AS Diff
FROM(
SELECT Name, Charge
FROM #ValuesTable
WHERE DateAdded BETWEEN DATEADD(day, -2, GETDATE())
AND DATEADD(day, -1, GETDATE())
) AS Y
FULL JOIN(
SELECT Name, Charge
FROM #ValuesTable
WHERE DateAdded BETWEEN DATEADD(day, -1, GETDATE()) AND GETDATE()
) AS T ON ISNULL(T.Name,Y.Name) = ISNULL(Y.Name,T.Name)
GROUP BY ISNULL(T.Name,Y.Name) , ISNULL(Y.Name,T.Name)

Answer 4

It may be just a typo in SO but if you are using date strings '14/10/2009' and '10/14/2009' in the same query it will never work.
No matter which date format you are using one of them has too many months in it.