ACC: How to Include a Null Selection in a Combo Box List

MORE INFORMATION

1. Open the sample database Northwind.mdb (or Nwind.mdb in 2.0).
2. Create the following query and save it as qryCustList:
   

         Query: qryCustList
         -------------------
         Type: Select Query
   
         Field: CustomerID
            Table: Customers
         Field: CompanyName
            Table: Customers
            Sort: Ascending
   						

   
   NOTE: In Microsoft Access 2.0, there is a space in the Customer ID and the Company Name field names.
3. On the View menu, click SQL View (or SQL in versions 7.0 or 2.0) and modify the SQL statement so that it reads as follows:
   

         SELECT DISTINCTROW Customers.[CustomerID], Customers.[CompanyName]
         FROM Customers
         UNION SELECT Null, Null FROM Customers
         ORDER BY Customers.[CompanyName];
   
         NOTE: In Microsoft Access 2.0, type a space in the Customer ID and
         the Company Name field names.
   						

   
   When you run this query, the combo box list is displayed with a top row of Null values, followed by the remainder of the customer list.
4. Create a new form not based on any table or query and save it as Test1:
   

         Form: Test1
         ------------------------------
         Caption: TestForm
   
         Combo box:
            Name: cmbTest
            RowSourceType: Table/Query
            RowSource: qryCustList
            LimitToList: Yes
         Text Box:
            Name: Field1
   						

5. Open the Test1 form in Form view.
6. Make a selection from the cmbTest combo box list and press TAB to move to the text box control. Note that this works as expected.
7. Return to the cmbTest combo box list, press DELETE, and then press TAB to move to the text box control.
   
   NOTE: By pressing DELETE, you have actually selected the first row in the list's RowSource, qryCustList.
8. Return to the cmbTest combo box list and enter Test. Press TAB to move to the text box control. Note that you receive the following error message, indicating that the LimitToList feature is enabled:
   
   In Microsoft Access 97 and 7.0:
   
   The text you entered isn't an item in the list.
   
   In Microsoft Access 2.0:
   
   The text you enter must match an entry in the list.