程序中的任何更改都不会影响数据库

问题是-当程序工作时，我在数据网格中更改，添加和删除数据。但是当我重新启动我的程序-它从数据库加载所有数据没有任何更改。(只添加数据工作)

哪里有问题?

 public partial class StudentsTable : Window
{
    public StudentsTable()
    {
        InitializeComponent();
    }
    CourseWorkFinal.University0DataSet university0DataSet;
    CourseWorkFinal.University0DataSetTableAdapters.StudentsTableAdapter university0DataSetStudentsTableAdapter;
    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        university0DataSet = ((CourseWorkFinal.University0DataSet)(this.FindResource("university0DataSet")));
        university0DataSetStudentsTableAdapter = new CourseWorkFinal.University0DataSetTableAdapters.StudentsTableAdapter();
        university0DataSetStudentsTableAdapter.Fill(university0DataSet.Students);
        System.Windows.Data.CollectionViewSource studentsViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("studentsViewSource")));
        studentsViewSource.View.MoveCurrentToFirst();
        university0DataSet.Students.StudentsRowChanged += new University0DataSet.StudentsRowChangeEventHandler(Modify);
        university0DataSet.Students.StudentsRowDeleted +=
            new University0DataSet.StudentsRowChangeEventHandler(Modify);
    }
    void Modify(object sender, University0DataSet.StudentsRowChangeEvent e)
    {
        university0DataSetStudentsTableAdapter.Update(university0DataSet.Students);
    }
    private void button1_Click(object sender, RoutedEventArgs e)
    {
        AddStudent x = new AddStudent();
        x.Show();
    }
    private void button2_Click(object sender, RoutedEventArgs e)
    {
    //    university0DataSetStudentsTableAdapter.Update(university0DataSet.Students);
    }
}