In the

Toolbox

, expand

Common Controls

, drag the

Button

control to the

CourseViewer

form designer, change the

name

of the control to

saveChanges

, and change the

Text

value to

Update

.

In the

CourseViewer

form designer, double-click the

saveChanges

control. This creates the

saveChanges_Click

event handler method.

Paste the following code that saves object changes to the database.

Visual Basic

Try
    ' Save object changes to the database, display a message,
    ' and refresh the form.
    schoolContext.SaveChanges()
    MessageBox.Show("Changes saved to the database.")
    Me.Refresh()
Catch ex As Exception
    MessageBox.Show(ex.Message)
End Try

C#

try
{
    // Save object changes to the database, display a message,
    // and refresh the form.
    schoolContext.SaveChanges();
    MessageBox.Show("Changes saved to the database.");
    this.Refresh();
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}

In the

closeForm_Click

event handler method, type the following code. This code disposes of the object context before the form is closed.

Visual Basic

   ' Dispose the object context.
    schoolContext.Dispose()

C#

    // Dispose the object context.
    schoolContext.Dispose();

From the

Debug

menu, select

Start Debugging

or

Start Without Debugging

, to build and run the application.

When the form loads, select a department from the

ComboBox

control to display the courses that belong to that department.

Figure 2.115. ComboBox

In the

DataGridView

, update course information or add a new course and then click

Update

to save changes to the database and displays a message box that declares the number of saved changes.

Figure 2.116. DataGridView