I'm not sure what you asked for. But I'm going to make an assumption that could well be wrong.
The only places where you have direct control over the color of something as a variable (i.e. red for this case, blue for that case) is on a Form in Form view or a Report in Normal or Preview view.
In tables, queries, forms, and reports in a datasheet view, you do not always have this level of control.
Particularly, because of the implications of datasheet view, you do not have the information that Access would need to help you change display attributes for a given field.
In mechanistic terms, a Form in form view (if it is a single-record form) has a Current event and an Update event for each record. Between these two events, you can compare a control's .Value and .OldValue properties to see if anything changed. Color changes could then be applied as needed on the form.
In datasheet view, I don't recall that ANY events are possible. If you set your cursor into a field and change it, then select the same field in a different row, you did an implied UPDATE by changing rows. I'm also not sure whether you can get code to run under a form in datasheet view other than functions that might be embedded in the underlying explicit or implied query.
Did that make sense in the context of your question?
