One of my greatest annoyances with Access is the fact that Microsoft in their infinite wisdom created a great field data type ‘Yes/No’ which you would think would be great for creating a Yes/No Option Group with. This is true if you want to have a default value, but what happens if you want to allow for a Null state, what is commonly referred to as a triple state field/Option Group, to allow for the case (a common situation in my experience) where you would like a Yes/No Option Group but leave it blank until the user actually makes a selection then the Yes/No data type no longer works?! You cannot have a Null value with a standard Yes/No Field.
So what is one to do?
Well, thankfully the solution is actually very simple. Change the data type from Yes/No to Number and change the Field Size to suit your particular needs. For instance, if like me, you wanted to assign -1 to Yes and 0 to No then you would have to change the Field Size to Integer.
