@bianhao不唯一

数据库更新过程中，带参数@bianhao，代码如下：

private void button1_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(nianji.Text) && !string.IsNullOrEmpty(banji.Text))
            {
                nianjibanji.Text = nianji.Text + banji.Text;
            }
            else
            {
                nianjibanji.Text= "";
            }
            SqlParameter parameter = new SqlParameter("@bianhao", SqlDbType.Char, 8);
            parameter.Value = bianhao.Text;
            mycmd.Parameters.Add(parameter);
            int age =Convert.ToInt32(nianling.Text);
            if (age<6&&age>20)
            {
                MessageBox.Show("请输入正确的年龄：");
                //mycmd.Parameters.Clear();
                return;
            }
            int bh = Convert.ToInt32(bianhao.Text);
            string xxmingch = xuexiaomingcheng.Text;
            string njbj = nianjibanji.Text;
            string xsxm = xueshengxingming.Text;
            string sex = xingbie.Text;
            string mz = minzu.Text;
            string csrq = chushengriq.Text;
            string jtzz = jiatingzhuzhi.Text;
            string jwbs = jiwangbingshi.Text;
            string qtbm = qitabingming.Text;
            string jwjzrq = jiwangjiuzhen.Text;
            string sg = shengao.Text;
            string tz = tizhong.Text;
            string xtys1 = shengaoyish.Text;
            string ssy = shousuoya.Text;
            string szy = shuzhangya.Text;
            string xtys2 = xueyayish.Text;
            string x = xin.Text;
            string f = fei.Text;
            string g = gan.Text;
            string p = pi.Text;
            string nkys = neikeyish.Text;
            string zy = zuoyan.Text;
            string yy = youyan.Text;
            string sy = shayan.Text;
            string jmy = jiemoyan.Text;
            string ykys = yankeyish.Text;
            string tb = toubu.Text;
            string jb = jingbu.Text;
            string xb = xiongbu.Text;
            string jz = jizhu.Text;
            string sz = sizhi.Text;
            string pf = pifu.Text;
            string lbj = linbajie.Text;
            string wkys = waikeyish.Text;
            string qc = quchi.Text;
            string yz = yahzou.Text;
            string kqys = kouqiangyish.Text;
            string fhl = feihuol.Text;
            string ys = qitayish.Text;
            string zc = zhengchang.Text;
            string xfc = xufucha.Text;
            string bm = bingming.Text;
            string jcys = jielunyish.Text;
            string zdyj = zhidaoyijian.Text;
            if (!string.IsNullOrEmpty(bianhao.Text)&&!string.IsNullOrEmpty(xxmingch)&&!string.IsNullOrEmpty(njbj)&&!string.IsNullOrEmpty(xsxm)&&!string.IsNullOrEmpty(sex))
            {
                int newrow=0;
                for (int i = 0; i < ds.Tables["dataTable"].Rows.Count; i++)
                {
                    int datavalue = Convert.ToInt32( ds.Tables["dataTable"].Rows[i]["编号"]);
                    
                    if (datavalue == bh )
                    {      //询问是否更新数据
                        if (MessageBox.Show("该编号信息已经存在，确定要修改吗？", "确认", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                        {
                            StringBuilder sb1 = new StringBuilder();
                            sb1.AppendFormat("Update xsxxlr set 学校名称='{0}',班级='{1}',姓名='{2}',性别='{3}',民族='{4}',出生日期='{5}'," +
                                "年龄={6},家庭住址='{7}',既往病史='{8}',其他病名='{9}',既往就诊日期='{10}',身高='{11}',体重='{12}',形体医生1='{13}'," +
                                "收缩压='{14}',舒张压='{15}',形体医生2='{16}',心='{17}',肺='{18}',脾='{19}',内科医生='{20}',左眼='{21}',右眼='{22}',沙眼='{23}'," +
                                " 结膜炎='{24}',眼科医生='{25}',头部='{26}',颈部='{27}',胸部='{28}',脊柱='{29}',四肢='{30}',皮肤='{31}',淋巴结='{32}'," +
                                "外科医生='{33}',龋齿='{34}',牙周='{35}',口腔医生='{36}',肺活量='{37}',医生='{38}',正常='{39}',需复查='{40}',病名='{41}'," +
                                "检查医生='{42}',指导意见='{43}',肝='{44}' where 编号=@bianhao", xxmingch, njbj, xsxm, sex, mz, csrq, age, jtzz, jwbs, qtbm, jwjzrq, sg, tz, xtys1,
                                ssy, szy, xtys2, x, f, p, nkys, zy, yy, sy, jmy, ykys, tb, jb, xb, jz, sz, pf, lbj, wkys, qc, yz, kqys, fhl, ys, zc, xfc, bm, jcys, zdyj, g);

                            mycmd.CommandText = sb1.ToString();
                            cn.Open();
                            mycmd.ExecuteNonQuery();
                            cn.Close();
                            MessageBox.Show("保存成功");
                            mycmd.Parameters.Clear();
                            newrow =1;
                            chongzhi();
                            gengxin();
                            return;
                        }
                        else
                            //mycmd.Parameters.Clear();
                            return;
                       
                    }
                }
                if (newrow == 0)
                {
                    StringBuilder sb1 = new StringBuilder();
                    sb1.AppendFormat("insert into xsxxlr(学校名称,班级,姓名,性别,民族,出生日期," +
                        "年龄,家庭住址,既往病史,其他病名,既往就诊日期,身高,体重,形体医生1," +
                        "收缩压,舒张压,形体医生2,心,肺,脾,内科医生,左眼,右眼,沙眼," +
                        " 结膜炎,眼科医生,头部,颈部,胸部,脊柱,四肢,皮肤,淋巴结," +
                        "外科医生,龋齿,牙周,口腔医生,肺活量,医生,正常,需复查,病名," +
                        "检查医生,指导意见,肝,编号)");
                    sb1.AppendFormat("Values('{0}', '{1}','{2}','{3}','{4}','{5}',{6}," +
                        "'{7}','{8}','{9}','{10}','{11}','{12}','{13}','{14}','{15}','{16}','{17}'," +
                        "'{18}','{19}','{20}','{21}','{22}','{23}','{24}','{25}','{26}','{27}','{28}'," +
                        "'{29}','{30}','{31}','{32}','{33}','{34}','{35}','{36}','{37}','{38}','{39}'," +
                        "'{40}','{41}','{42}','{43}','{44}',{45})",xxmingch, njbj, xsxm, sex, mz, csrq,age, jtzz, jwbs, qtbm, jwjzrq, sg, tz, xtys1,ssy, szy, xtys2, x, f, p, nkys, zy,yy, sy, jmy, ykys, tb, jb, xb, jz, sz, pf, lbj, wkys, qc, yz, kqys, fhl, ys, zc,xfc, bm, jcys, zdyj, g,bh);
                    mycmd.CommandText = sb1.ToString();
                    cn.Open();
                    mycmd.ExecuteNonQuery();
                    cn.Close();
                    MessageBox.Show("保存成功");
                    chongzhi();
                    gengxin();
                    //mycmd.Parameters.Clear();
                    return;
                }

            }
            else
            {
                MessageBox.Show("请输入基本信息！");
               // mycmd.Parameters.Clear();
                return;
            }
            
        }

在每个return前，加入参数列表的清空，

mycmd.Parameters.Clear();
return;

或者在数据更新前再装载参数@bianhao