Combo boxes have most of the same properties, events, and methods as list boxes.

Combo and list boxes are among the most powerful and versatile controls in Access. They allow you to control data entry by limiting the options to existing items, but you can do much more than that. The articles on this page will demonstrate some of the things you can do with combo boxes.

Combo box techniques

To create a combo box, you can do one of the following (in Design view on a form or report):

• Select the combo box icon in the Tools menu, and click on the form
• Right-click an existing text box or list box, and Change To > Combo Box

Important combo box properties

If you go to the All tab of a combo box's properties, you will see a long list. Some of these properties will be used every time you setup a combo box; they are listed below.

Cascading combo boxes: filtering one combo on the basis of another combo box

It is often useful to be able to select a category from one combo box and then select items belonging to that category, using a second combo box. Setting this up requires 3 steps, which are detailed below, using the Northwind sample database.

Step 1: Create the first combo box

In the Northwind database, create a new form and call it frmChooseProducts. Add 2 combo boxes to the form; name the first cmbSuppliers, and the second cmbProducts. Set the properties of cmbSuppliers as follows:

Click the thumbnail to see the query grid for cmbSuppliers

Step 2: Create the second combo box

Set the properties of cmbProducts as follows:

Click the thumbnail to see the query grid for cmbProducts

Step 3: Add code to the first combo box that re-queries the second combo box

Now, go back to cmbSuppliers. In the properties, select the Events tab and create the following code in the After Update event of the cmbSuppliers (check HERE if you don't know how to create an event procedure):

The After Update event is triggered once you have made a selection in the combo box; the Requery method re-evaluates the SQL behind cmbProducts, so that the combo displays the appropriate list when the user selects the drop-down. Save the form, switch to Form view, and give it a try.

Update: A newer article shows a technique that works on continuous forms.

Letting users choose any item from the second combo box

Sometimes you want to switch between having the second combo box dependent on the first, and being able to select any value. This tip shows one way to achieve that -- by modifying the Row Source of the second combo. Change the AfterUpdate event for cmbSupplier to this:

If you clear cmbSuppliers, the above code removes the WHERE clause that makes cmbProducts dependent on cmbSuppliers. If cmbSuppliers has anything in it, the code resets cmbProducts to make it dependent on cmbSuppliers again.

For the user, this means that you can decide whether or not to make the second combo box dependent on the first.

Finding or filtering records with a combo box

On a data entry form with many records, you may need to find a unique record or filter for all records matching a particular value. in both cases you can use a combo box to narrow down the search item. The next two articles show how to do this.

Finding a unique record

This example uses the Suppliers form in the Northwind sample database. When we make a selection from the combo, we will move to the selected supplier without filtering the form. Hence, this technique allows you to continue browsing the rest of the form's records without having to remove a filter. Do the following:

• Open the Suppliers form in Design view
• Open the Form Header to a height of 1cm, and add a new combo box to the header. Set up the combo box with these properties:
• Note -- the combo box is unbound (does not have a Control Source) because it is used for searching, not for data entry.

The query grid for cmbSupplierSearch looks like this:

To navigate to the correct location, we need to move to the record whose ID matches the selected supplier. We can do this by using the record's bookmark in the form's recordset. The following code goes into the After Update event of the combo, which is triggered when you make a selection from the list.

For a tip on creating event code in Access, see this page

Click the thumbnail to see the finished form. When you select a supplier, you navigate to that record.

Filtering for records that match a particular value

The Find technique works well if the record is unique. But if you need to see all orders from a particular client, a filter is required. This technique filters the Orders form in the Northwind database.

• Open Orders in Design view. View > Form Header/Footer to display the header and footer; set the height of the header to 1cm, and the height of the footer to 0.
• Add a combo box to the form header. This combo will also be unbound, and needs to have the properties:

Now to add the code that filters the form. It will go in the AfterUpdate event of the combo box:

Click the thumbnail to see the completed form