private void btnUpdate_Click(object sender, EventArgs e)

        {

            SqlConnection cn = new SqlConnection(Properties.Settings.Default.XkConnectionString);

            string sql = "DELETE FROM StuCou WHERE StuNo=@StuNo";

            SqlCommand cmd = new SqlCommand(sql,cn);

            cmd.Parameters.Add("@StuNo", SqlDbType.NVarChar, 8).Value = CPublic.LoginInfo["StuNo"].ToString();

            cn.Open();

            cmd.ExecuteNonQuery();

            cn.Close();



            for (int i = 0; i < dgvSelectCourse.Rows.Count; i++)

            {

                sql = "insert StuCou(StuNo,CouNo,WillOrder,State) values(@StuNo,@CouNo,@WillOrder,@State)";

                cmd = new SqlCommand(sql,cn);

                cmd.Parameters.Add("@StuNo",SqlDbType.NVarChar,8).Value=CPublic.LoginInfo["StuNo"].ToString();

                cmd.Parameters.Add("@CouNo", SqlDbType.NVarChar, 8).Value = dgvSelectCourse.Rows[i].Cells["SelectCouNo"].Value;

                cmd.Parameters.Add("@WillOrder",SqlDbType.SmallInt).Value=i+1;

                cmd.Parameters.Add("@State", SqlDbType.NVarChar, 2).Value = "报名";



                cn.Open();

                cmd.ExecuteNonQuery();

                cn.Close();

            }

            ds.Tables["StuCou"].Clear();

            getStuCou();

        }