MS Access™ MVP Awardee: 2007-2017
Blog: GPG on Access
Published Books:
Professional Access 2013 Programming with co-authors Teresa Hennig, Ben Clothier and Doug Yudovich. Grover Park George On Access MS Access™ in a SharePoint World with co-authors Tim Runcie and Ben Clothier.
Combo and List Boxes are very useful when you want to display to your user a list of choices or a list of existing records. For example, you may offer your users a list of Employees and a list of available Vehicles from which to choose in checking out a company vehicle to an employee. Most list and combo boxes have multiple columns, including one for the bound column of the selected option (usually this is the Primary Key of the source table for the control ), and one or more columns which display the choices in plain language. These value columns allow users to select from meaningful options, rather than forcing them to remember potentially obscure values. The Bound Column property tells Microsoft Access which column's values to use as the control source of the control. It should be the column which contains the Primary Key from the lookup table which provides the values for the control. Normally the bound column will be the leftmost column in a combo or list box. When a user clicks on a name in the list to select an employee, the value of the bound column (i.e. the Primary Key from the Employee table) is saved to the vehicle checkout table, in the foreign key field that identifies the Employee checking out the vehicle. Normally, you will set the width of the bound column to 0 (i.e. zero inches), meaning that it is not visible to users. You want users to see only the natural language choices, not the primary key (foreign Key) itself. That can only confuse things. Potential for Confusion: Indexes versus column numbers. "Microsoft Access uses a zero-based index to refer to columns in the Column property. That is, the expression Column(0) refers to the first -- or left-most -- column; Column(1)refers to the second column from the left; and so on. However, the Bound Column property uses 1-based numbers to refer to the columns. This means that if the Bound Column property is set to 1 (the leftmost column) , you access the value stored in that column by using the expression Column(0)."