T-SQL to sum total value instead of rejoining table multiple times - sql-server

Question

I've looked for an example question like this, I ask for grace if it's been answered (I thought it would have been but have a hard time finding meaningful results with the terms I searched.)
I work at a manufacturing plant where at ever manufacturing operation a part is issued a new serial number. The database table I have to work with has the serial number recorded in the Container field and the previous serial number the part had recorded in the From_Container field.
I'm trying to SUM the Extended_Cost column on parts we've had to re-do operations on.
Here's a sample of data from tbl_Container:
Container From_Container Extended_Cost Part_Key Operation
10 9 10 PN_100 60
9 8 10 PN_100 50
8 7 10 PN_100 40
7 6 10 PN_100 30
6 5 10 PN_100 20
5 4 10 PN_100 50
4 3 10 PN_100 40
3 2 10 PN_100 30
2 1 10 PN_100 20
1 100 10 PN_100 10
In this example the SUM I would expect returned is 40, because operations 20, 30, 40 and 50 were all re-done and cost $10 each.
So far I've been able to do this by rejoining the table to itself 10 times using aliases in the following fashion:
LEFT OUTER JOIN tbl_Container AS FCP_1
ON tbl_Container.From_Container = FCP_1.Container
AND FCP_1.Operation <= tbl_Container.Operation
AND tbl_Container.Part_Key = FCP_1.Part_Key
And then using SUM to add the Extended_Cost fields together. However, I'm violating the DRY principle and there has got to be a better way.
Thank you in advance for your help,
Me

Answer 1

You can try this query.
;WITH CTE AS
(
SELECT TOP 1 *, I = 0 FROM tbl_Container C ORDER BY Container
UNION ALL
SELECT T.*, I = I + 1 FROM CTE
INNER JOIN tbl_Container T
ON CTE.Container = T.From_Container
AND CTE.Part_Key = T.Part_Key
)
SELECT Part_Key, SUM(T1.Extended_Cost) Sum_Extended_Cost FROM CTE T1
WHERE
EXISTS( SELECT * FROM
CTE T2 WHERE
T1.Operation = T2.Operation
AND T1.I > T2.I )
GROUP BY Part_Key
Result:
Part_Key Sum_Extended_Cost
---------- -----------------
PN_100 40