Creating Cascading Combo Boxes and List Boxes on Microsoft Access Forms

by Molly Pell, Senior Systems Analyst

Sample database: CascadingComboBoxes.zip (62 KB)

The Problem

Combo boxes and list boxes are a great way to control user experience by limiting the values that a user can choose to a known list.

In Microsoft Access, a common need is to have multiple combo boxes or list boxes on a form, and to have the selection in one combo box limit the choices in a second combo box. For example, an Address form containing Country and State lookups. When you select a country, its list of states appear.

Our this sample database, we have a list of species, both plants and animals, categorized by their taxonomic rank (kingdom, phylum, class, order, family, genus, then species).

If you select the value "Animal" from the Kingdom combo box, the Phylum combo box is updated to show Animal phylums only. The Species list box is also filtered by your selection.

This is known as cascading combo boxes or synchronized combo boxes.

The Solution

To create the cascading combo box, we add code in the "AfterUpdate" event for the Kingdom combo box, to update the RowSource property of the Phylum combo box based on the selected Kingdom.

' Set the Phylum combo box to be limited by the selected Kingdom
Me.cboPhylumID.RowSource = "SELECT PhylumID, PhylumName " & _
                           "FROM tblPhylum " & _
                           "WHERE KingdomID = " & Nz(Me.cboKingdomID) & _  
                           "ORDER BY PhylumName"

Additionally, we add code to update the contents of the Species list box:

' Limit the Species list box
Me.lstSpeciesID.RowSource = "SELECT SpeciesName, Description " & _  
                            "FROM qryTaxonomy " & _  
                            "WHERE KingdomID = " & Me.cboKingdomID 
' Refresh the list box
Me.lstSpeciesID.Requery

After updating the RowSource property, use the list box's Requery method to re-load the data in the ListBox.

RecordSource versus RowSource

There is sometimes confusion between the terms RecordSource and RowSource. Both are properties that can contain a table, query, or SQL string.

• The RecordSource property is a form or report property to populate the data that Microsoft Access displays for that object.
• The RowSource property is at the ComboBox or ListBox control level that tells Microsoft Access what data to display for the control. It is independent of the data specified by the object's RecordSource.

Microsoft Resource: How to: Synchronize Two Combo Boxes on a Form

Resources for Microsoft Access Forms, Combo Boxes and Tabs

• Top Five Tips for Using Combo Boxes on Microsoft Access Forms
• Creating Cascading Combo Boxes and List Boxes on Microsoft Access Forms
• Tips and Techniques for Using and Validating Microsoft Access Combo Boxes
• Using Combo Boxes to Auto-Fill City and State from USPS Zip Code Database
• Synchronize Two Related Subforms on a Microsoft Access Form
• Performance Tip: Use Late Binding for Microsoft Access Subforms on Tab Pages
• Reference Tab Pages by its PageIndex Rather than Tab Value on Microsoft Access Forms
• Using the Form Navigation Caption in Microsoft Access 2007, 2010 and 2013
• Microsoft Access Form Design Tips
• Microsoft Access Form Tips and Avoiding Common Mistakes
• Microsoft Access Developer and Programming Help Center