ACC: Base Combo Box on Parameter Query to Filter Values (99937)

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Sometimes, you may want to limit the values that appear in a combo box. For example, you may want to show only suppliers whose names begin with a certain letter. Although Microsoft Access does not allow filters on combo boxes, if you base your combo box on a parameter query, you can filter the values by using a criteria clause.

This article describes the steps to create a combo box that displays only the suppliers that meet the criteria that you specify. The example uses the sample database Northwind.mdb (or Nwind.mdb in versions 1.x and 2.0).

1. Open the sample database Northwind.mdb.
2. Create the following query based on the Suppliers table to use as the row source in the combo box:
   

         Query: Filtered Supplier List
         -----------------------------
         Type: Select
         Field: CompanyName
            Table: Suppliers
            Sort: Ascending
            Criteria: Like [My Criteria Box] & "*"
   						

   NOTE: In versions 1.x and 2.0, there is a space in Company Name.
3. Create the following macro to update the combo box with new criteria:
   

         MacroName: CB Test Macro
         ------------------------
            Action: Requery
            ControlName: My Combo Box
   						

4. Create the following unbound form to test your controls:
   

         Form: TestForm
         --------------
         Caption: Test Filtered Combo Box
   
         Combo Box:
            Name: My Combo Box
            RowSourceType: Table/Query
            RowSource: Filtered Supplier List
         Text Box:
            Name: My Criteria Box
            After Update: CB Test Macro
   						

5. Open TestForm in Form view and click the arrow on the combo box. Note that all suppliers appear in the list.
6. Type a single letter in My Criteria Box (for example, the letter E).
7. Click the arrow on the combo box. Note that only suppliers whose names begin with the letter "E" are displayed.
8. Type a new letter in My Criteria Box (for example, the letter P).
9. Click the arrow. Note that although the combo box value still shows a company starting with "E" (if you selected one), only suppliers whose names begin with the letter "P" are displayed in the list.