Maybe something like this:
SELECT StudentID,
FirstName,
Course ,
Score ,
(CAST(Score AS numeric( 10, 4)) / SUM(Score) OVER( PARTITION BY StudentID)) * 100
FROM Studentgrades
Look for information on the OVER clause or window functions.
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2