If you have hidden fields in the attribute table, then they will not show up in Field Calculator. In the attribute table, go to Table Options, and then Turn all Fields On.



The key to note here is "in other dialogs". If you hide them here, they will be invisible to most other tools, identify, export, etc.

Field Calculator not showing some fields
I have an application where I need to do nearest neighbor, rectangle/polygon overlap and other basic computational geometry operations against dynamically changing data (all 2d.)  I understand the basic data structures in the static case (quadtrees, 2-dimensional Kd-trees, R-trees, BSP, etc.) but I want to understand the state of the art in the dynamic case.  The difficulty seems to be knowning when/how to balance on insertion and deletion.  For example, is there a dynamic data structure that answers k-nearest neighbors against n points in O(log n + k), where insertion and deletion take O(log n) (amortized, maybe)?  Is there a standard reference that summarizes what's known about this problem?
