private void button3_Click(object sender, EventArgs e)
{
InputStudentForm isf = new InputStudentForm();
isf.MdiParent = this.MdiParent;
isf.Show();
}
private void btnUpdate_Click(object sender, EventArgs e)
{
Student st = StudentManageAction.QueryStudentInfo(tbStudentNo.Text);
InputStudentForm asf = new InputStudentForm(st);
asf.MdiParent = this.MdiParent;
asf.Show();
}