Update using field value

Is it possible to use value of a field in update

1 Value of another field - ie update field 1 so it is equal to field 2 I have tried various syntaxes using formulas etc but nothing works

2 update a field using the fields current value in a formula - for instance need to either increase or decrease a field by a set amount (In this case 1 so new value of field 1 = (old value field 1) -1

This is fairly trivial in our current database but I can not see how to achieve in Knack