[sql] How to do a SUM() inside a case statement in SQL server

If you're using SQL Server 2005 or above, you can use the windowing function SUM() OVER ().

case 
when test1.TotalType = 'Average' then Test2.avgscore
when test1.TotalType = 'PercentOfTot' then (cnt/SUM(test1.qrank) over ())
else cnt
end as displayscore

But it'll be better if you show your full query to get context of what you actually need.