I'm trying to update the following table:

Column1 Column2
Data1 X+2
Data2 X+1
Data3 X



X = User defined input

I would like to create an update query that will update Column2 to X where Column1 = Data3 but then automatically calculate and update the values in Column2 to X+2 and X+1 for Data1 and Data2.

How can I do this in a single Update Query? So far, I have only been able to update Column2 for Data3.

Thanks for your help....