ABC ~ All 'Bout Computers
The Online Web-azine for Computer Enthusiasts
-- brought to you by

contents page for this issue

James's Database
~~James La Borde

Combo and List Boxes in MS Access
- What They Are and When To Use Them

These items are both commonly used and unfortunately quite misunderstood. While both extremely useful, they are also confusing to many new users of Access. Let's take a look at what each of them is and then delve into the key differences.

List Boxes
List Boxes are exactly what the name implies; they are boxes that display a list of values for the user to select from. This eliminates the need to remember the correct value to type and prevents typos from corrupting your data. List Boxes are static items and the user is unable to enter new items in the field. List boxes are capable of displaying multiple columns, however, only one column is stored in the field.

List Boxes have a number of advantages and disadvantages. One of the key advantages is that you can allow the user to select multiple items from the list box. If you enable this option, the user can do this by merely holding down the CTRL key and selecting any items they desire. The restriction on entering new data can be an advantage. One of the primary disadvantages of a list box is that it takes up a lot of space. The box displaying all of the values can be quite large if you display too much.

When would you use a list box? Any time the options are static and you have the room on your form or need to allow the user to select multiple options. For instance, shipping options remain relatively static, if you were to design a form with Shipping Options listed you might want to opt for a list box. Another use would be when you are allowing multiple entries. Let's say you are doing a vehicle database and want to include a list of options. Rather than make a separate field for each potential option, you merely list them all in a list box and allow the user to select as many options as are available.

Combo Boxes
The function of a combo box is not as readily apparent from the name as a list box. A combo box is a control that allows the user to select an item from a drop-down list. Combo boxes are very similar to list boxes, which is where the confusion comes in. There is more to the difference than just how they appear. Combo boxes give the developer the option of allowing the user to enter additional options if the situation warrants.

As with List boxes there are both disadvantages and advantages to the combo box. Some of the advantages include the ability to add to the list, and they are space saving since the list does not display until the user selects the pull down. The primary disadvantage is that the user is limited to a single selection.

When should you use a combo box? The main thing to remember here, the user can only select one option in a combo box. You may also want to consider if you want your user to be able to add additional items to those already listed. For instance, if you are creating a books database, you could use a combo box for authors. Once an authors name is listed it is not likely to change, but as the users tastes and collection grow, they may need to add additional authors.

What they have in Common
There are many similarities between list and combo boxes. They are both essentially lists of values that the user can select the desired value from. Both can be bound to a table and display multiple columns while storing only a single value. One extremely useful aspect of these two controls is that they can be left unbound and simply used as input options for another control. Both have the ability to restrict the user from entering potentially erroneous information.

James La Borde works in the computer department at a Credit Union, where he uses Access, SQL Server, VBA, and ODBC daily.  He also teaches online Access classes at Eclectic Academy.