The source code in this issue is designed for Visual Basic 4 and 5. With some modifications it should be able to run in VB3 as well.
This issue shows how to load a combo box with some information from a database table. It is useful for those combo boxes in your application such as Payment methods or Shipping methods where there are several methods, but they need to be configurable. Since they need to be configurable you store them in a database table. Using the combo box this way is more flexible than using the DBComboBox since it does not have to be bound to a data control.
Public Sub DBLoadCombo(sDB As String, sSQL As String, cmb As ComboBox, sDisplayField As String, sIDField As String)
Some people probably are not familiar with the ItemData feature. The Visual Basic Help file describes it as such:
"The ItemData property is an array of long integer values with the same number of items as a control's List property. You can use the numbers associated with each item to identify the items. For example, you can use an employee's identification number to identify each employee name in a ListBox control. When you fill the ListBox, also fill the corresponding elements in the ItemData array with the employee numbers. The ItemData property is often used as an index for an array of data structures associated with items in a ListBox control."
The only limitation to the ItemData property is that the data type is a Long. It some way it would be nice if it were a Variant, but it would not be as efficient.
You will probably want to set the Style property of the combo box to "2 - Dropdown List."
None unless an error occurs. If an error occurs it will be raised to the caller.
The below example uses the DBLoadCombo routine to fill the cmbPaymentMethods combo box with all the available payment methods.
sDBName = "C:\COTW\COTW.MDB"
DBLoadCombo(sDBName, "SELECT * FROM TABLE", cmbPaymentMethods, "Description", "ID")
The resulting combo box will contain something like this:
List Array:
Visa
MasterCard
American Express
ItemData Array:
0
1
2
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In the last issue we mentioned a Visual Basic class for adding fields, indexes, queries and other database objects from VB. We are still working on this class. As soon as we complete it, it will appear in Code of the Week. If you have any other database operations you are interested in getting information about, please let us know at our feedback page at http://www.codeoftheweek.com/feedback.html
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