//导入了学生才直接跳到考勤界面，否则跳到添加学生界面
private void Picture_Click_checkStu(object sender, EventArgs e)
{
PictureBox p = (PictureBox)sender;
DataTable dt = teacherBll.getCourseIdAndNum(tea_id);
cou_id = dt.Rows[Convert.ToInt32(p.Name)][0].ToString();
cou_num = dt.Rows[Convert.ToInt32(p.Name)][1].ToString();
checking c = new checking(tea_id, cou_id, cou_num);
c.Show();
this.Hide();
}