In this section the changes made to Course objects bound are saved to the DataGridView control to the database and also run the completed Course Manager application.

Save changes made to objects

  1. 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

    .

  2. In the

    CourseViewer

    form designer, double-click the

    saveChanges

    control. This creates the

    saveChanges_Click

    event handler method.

  3. 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);
    }
    
  4. 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();
    

Build and run the Class Scheduling application

  1. From the

    Debug

    menu, select

    Start Debugging

    or

    Start Without Debugging

    , to build and run the application.

  2. When the form loads, select a department from the

    ComboBox

    control to display the courses that belong to that department.

    Figure 2.115. ComboBox

    ComboBox

  3. 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

    DataGridView

The process is now complete