The vast majority of forms are built on the data from a single table. Access makes it very easy to change the control source of an object. Open the form in Design view, click the object that you want to change the data source and click the Properties icon (). When the Properties dialogue box appears, click the Data tab. Adjust the Control Source field by using the combo box:

 

 

In the example above, the values in the combo box are the field names of the table that the form is built upon; in this case, the Categoried table from the Northwind sample database. If you want to add the values from some other database object, click the () button. This will open the Expression Builder dialogue box:

 

 

The Expression Builder lets you do a number of things. You can construct logical expressions, extract information from queries, and create calculations. In the diagram above, the new control source would be the first name of an employee. This application doesn’t make much sense, but the Expression Builder makes it easy to change the control source with only a few clicks.