So I hope this makes sense. I have a column within a list that I want to use as an active flag. There are 5 possible categories and for each category, there can only be one active value. So I need some method that if a user selects category 2, and makes it active, then the previous category 2 active value no longer is active.

Could I achieve this by adding SPServices and jQuery to the edit form (probably new too I guess), and just use a CAML value to find this value and update it? How would I be able to narrow it to that other ID?

Does this even make sense? :) Thanks as always guys!

EDIT: restarting in an attempt to clarify another one of my bizarre questions. 

Is it possible to achieve something like having a choice field with options 0-5, where option 0 is not unique, but option 1-5 are? Probably not within the built-in SharePoint construct of the choice field and red button, but is there a way to combine some jquery with that in order to achieve the same result. So I don't care how many zeros there are throughout the lists, multiple items can all be ranked zero, but I need ranking 1 to 5 to be unique. If 1 is the value of this field on itemID=312, then how to prevent it if itemID=311 also equals 1, or change that value from 1 to zero for itemID=311?? This sounds weird I know but it is exactly what I need for an automated ranking system that pulls content and builds pages dynamically based on user selections.