Microsoft Visual Basic 2010 Step by Step eBook

Chapter 19 Data Presentation Using the DataGridView Control 485

Adding a BindingNavigator Control to Create

a Second Navigation Bar on the Form

If you choose to add a second database table to your form, keep in mind that you can

also add a second navigation bar to the form so that your user can use two different

navigation bars at once. To make this work, you need to be using a database that

contains more than one table. (In the Faculty2010 .accdb database, there was only one

table, but it is common for databases to have several tables to choose among .) Follow

these steps to add a second table and navigation bar to your program:

1. Use the Data Sources window to create a second data grid view object on your
   form, representing a second table in the database.


2. Customize the table’s fields by setting properties and using the Edit Columns
   command.


3. Double-click the BindingNavigator control on the Data tab of the Toolbox.
   Visual Studio adds a binding navigator object named BindingNavigator1 to the
   component tray and adds a second navigation bar to the top of your form. You
   may need to move the data grid view objects down slightly if the new navigation
   bar is covering them.


4. Change the BindingSource property of the second binding navigator object to
   the binding source of the second table. This is made easy by the BindingSource
   arrow in the Properties window, which shows the names of the two valid binding
   sources in the program, so you can simply pick it from the list. Once a link has
   been established between the second navigation bar and the binding source
   object representing the second table, your program is ready to run.

One Step Further: Updating the Original Database

As I mentioned earlier, the dataset object in your program is only a representation of the

data in your original database. This is also true of the information stored in the data grid view

objects on your form—if the user makes a change to this data, the change isn’t written back

to the original database unless you have set the data grid view object’s ReadOnly property

to False and the user clicks the Save Data button on the navigation bar. The designers of

ADO .NET and Visual Studio created this relationship to protect the original database and to

allow your users to manipulate data freely in your programs—whether you plan to save the

changes or not.

In the following exercise, you’ll examine the first data grid view object’s ReadOnly property,

which enables or disables changes in the FacultyDataGridView object. You’ll also learn how

to use the Save Data button, which writes changes back to the original database tables

on disk.