Search multi-valued field

[agibsonsw]

Hello. Access 2007.
A colleague wants to use a combo-box as search criteria to display a second form. The second forms' recordsource is a query that use the criteria
IIf([Forms]![frmSwitchboard]![CboStage] Is Null,([Investors].[Stage].[Value]) Like "*",[Forms]![frmSwitchboard]![cboStage])
It's using [Stage].[Value] as [Stage] is a multi-valued field.
Stage is a number field so I tried amending the expression to [Stage].[Value]>0 but it still shows no records if no value is selected from the combo box.
It does work, however, if a value is selected from the combo box.
Is it possible to get this to work? Is it because the field is multi-valued that the above expression(s) won't work? Thanks, Andy.

[HansV]

What is the purpose of the expression ([Investors].[Stage].[Value]) Like "*" ? In this form, it's not valid, whether Stage is a multivalued field or not.

[agibsonsw]

Hello.
If nothing is selected from the cboStage combo box we want to display all the records. Andy.

[HansV]

Try this as criteria:

[Forms]![frmSwitchboard]![CboStage] Or [Forms]![frmSwitchboard]![CboStage] Is Null

[agibsonsw]

Great, that works.
He also wants to allow (somehow) the choice of two stages to use in the search criteria. That is, to have an option "This Or That" to appear in the combo box.
I am aware that I can do this using a Union Query to add a 'fake' record to the drop-down list. However, am I likely to encounter substantial difficulties because
this field is multi-valued? Thanks, Andy.

[HansV]

You can't select multiple items from a combo box.

One option would be to use two combo boxes. Another would be to use a multi-select list box, but that would require some VBA.

[agibsonsw]

Thanks.

[Egg 'n' Bacon]

How about setting the default value of the combo box to "*".

[HansV]

That's possible too; in that case, the criteria should be

Like [Forms]![frmSwitchboard]![CboStage]