大加帮我看看先面的代码啊
    到底是什么错误 啊??????   很急啊   啊    错误:"在位置 0 处没有任何行。"
   为什么在位置 0 处没有任何行。啊
   有谁能帮帮我吗???????

            string sql1 = "SELECT  student.ID,BJ.BJDM,kecheng.KCDM FROM  BJ CROSS JOIN kecheng CROSS JOIN student where student.ID='"+texIDcj.Text+"' and BJ.BJDM='"+combBJMC.Text+"' and kecheng.KCDM='"+comboKCMC.Text+"'";


            DataSet da1 = new DataSet();    //把数据放在内存中
            SqlDataAdapter adp1 = new SqlDataAdapter(sql1,str1);   //更新数据库
            da1.Clear();    //清空数据
            adp1.Fill(da1,"wwwq");
            string ID= da1.Tables[0].Rows[0][0].ToString();
            string BJDM=da1.Tables[0].Rows[0][1].ToString();
            string KCDM= da1.Tables[0].Rows[0][2].ToString();

  //录入成绩
            string sql = "insert into cjbiao(id,kcdm,bjdm,cj) values('" + ID + "','"+KCDM+"','" +BJDM+ ",'" + texCj1.Text + "')";
            
            SqlCommand cmd=new SqlCommand(sql,con1);
            con1.Open();
            cmd.ExecuteNonQuery();
            con1.Close();


            MessageBox.Show("班级信息添加成功", "提示");