ACC2000: Base Combo Box on Parameter Query to Filter Values

This article shows you how to filter values that appear in a combo box by basing the combo box on a parameter query.

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 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.

To create a combo box that displays only the suppliers that meet the criteria that you specify, follow these steps.

CAUTION: If you follow the steps in this example, you modify the sample database Northwind.mdb. You may want to back up the Northwind.mdb file and follow these steps on a copy of the database.

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 Query
   
      Field: CompanyName
      Table: Suppliers
      Sort: Ascending
      Criteria: Like [My Criteria Box] &"*"
   					

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 form not based on any table or query 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 the TestForm form in Form view, and click the arrow in the combo box. Note that all suppliers appear in the list.
6. Type a single letter in the text box (for example, the letter "E").
7. Click the arrow in the combo box. Note that only suppliers whose names begin with the letter "E" are displayed.
8. Type a new letter in the text 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.

For more information about creating combo boxes, click Microsoft Access Help on the Help menu, type creating and editing combo boxes in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.

For more information about creating criteria queries, click Microsoft Access Help on the Help menu, type creating criteria queries in the Office Assistant or the Answer Wizard, and then click Search to view the topics returned.