Help with Update query including JOIN

Question

Hi,
This is my first post to this forum and really hoping someone is able to help me write an update query.
Here is my data model:
Table (Columns)
Services (ServiceCode, BranchID, GLCodeGUID)
GLCodes (GLCodeGUID, BranchID, GLCode)
I have added valid GLCode data to the Services table for BranchID = 99
I would like to update all other branch records in the service table to their corresponding GLCodeGUID values  matched by GLCode.
This is the query I have come up with so far which is incorrect.
UPDATE S
SET S.GLAccountCodeGUID = G.GLCodeGUID
FROM Services S
JOIN GLCodes G
ON G.GLCodeGUID = S.GLAccountCodeGUID
JOIN Services SM
ON S.ServiceCode = SM.ServiceCode and SM.BranchID = 99
WHERE S.BranchID != 99
AND S.IsActive = 1
ORDER BY S.ServiceCode

Answer 1

Received some assistance from a work colleague and solved this with the following Query:
UPDATE s2 SET s2.GLAccountCodeGUID = gl2.GLCodeGUID
FROM Services s1
JOIN GLCodes gl1
ON s1.GLAccountCodeGUID = gl1.GLCodeGUID
JOIN GLCodes gl2
ON gl1.GeneralLedgerCode = gl2.GeneralLedgerCode AND gl1.BranchID <> gl2.BranchID
JOIN Services s2
ON s1.ServiceCode = s2.ServiceCode AND s1.ServiceCode = s2.ServiceCode AND s1.BranchID <> s2.BranchID
WHERE s1.BranchID = 99 AND gl1.BranchID = 99 AND
s2.BranchID = 2 AND gl2.BranchID = 2