Good design using triple state

[Leif]

My client needs to show a triple state field. It is a field called OID
Req'd. The client wants to know three possible (mutually exclusive)
conditions:

1. Field never set
2. Field set is Yes
3. Field set to No

My initial plan was to use a triple state checkbox. However, that has two
drawbacks.

1. Cannot use boolean Yes/No. I need to use a integer.
2. Field never set (Null) shows as a grayed-in box in form, but in datasheet
view there is no distinction between a Null value and a No value.

Have you come up with a good design solution for this general problem? Also
consider was

1. Radio button - Takes up more screen space
2. Drop down box - Not good design (IMO) for two options (plus Null)

Thanks,
Leif

 

[Allen Browne]

Leif, as you say, the check box does not display reliably. The actual
display problems depend on the version of Windows, plus the setting for
Themed Controls in Access.

Combo is probably the most obvious interface to go for.
I recommend combos for triple-state.

BTW, using an integer field is actually an advantage over the JET yes/no
field, since JET can crash when you operate on a yes/no field that contains
Null (typically due to subquery or outer join.)

More info here:
Why I stopped using Yes/No fields
at:
http://allenbrowne.com/NoYesNo.html