void GetBan()
{
TeacherBLL Teacher = new TeacherBLL();
cmbbanname.DisplayMember = "教师姓名";
cmbbanname.ValueMember = "教师编号";
cmbbanname.DataSource = Teacher.GetAllTeacher();
}
void GetAllTeacher()
{
TeacherBLL teacher = new TeacherBLL();
databanzhuren.DataSource = teacher.GetAllTeacher();
}