I think i need a recursive update to do this (to avoid cursors) - but i am not sure if I can do that in SQL and/or if in fact it's what I need to do!

The problem:

Table currently has the wrong values in a field and I need to update the entire table with the right values. The values depend on previous values in the table - like a running total for example (it's actually a conditional total but I can handle that bit). So record X depends on the new value of all records before it being updated already - hence the idea of recursion.

I currently have a cusor solution that works, but it takes a long time to run as soon as I get to 50000+ rows - and I figure that there has to be a better way. Or maybe not?

The key issue is being able to run a single update that 'knows' what the new values are. I'm not sure replicating the code would help - the idea is simple enough and the code for my real example is long in the context it is in.