奇怪的SqlDataAdapter.Update(Dataset)问题....请高手进来帮忙搞定

   using(SqlConnection conn = new SqlConnection(ConfigHelper.IagentDBConnectString))
   {
    if(conn.State!=ConnectionState.Open)
    {
     conn.Open();
    }
    SqlDataAdapter sda = new SqlDataAdapter("select * from TProductPrice where pid="+p_ProductPriceArr[0].PID,conn);

    DataSet ds = new DataSet();
    sda.Fill(ds);

    //清除PID的价格记录
    for(int i=0;i<ds.Tables[0].Rows.Count;i++)
    {
     ds.Tables[0].Rows[i].Delete();
    }
    //增加新记录
    for(int i=0;i<p_ProductPriceArr.Count;i++)
    {
     DataRow  dr = ds.Tables[0].NewRow();

     dr["PID"] =  p_ProductPriceArr[i].PID;
     dr["LevelID"] = p_ProductPriceArr[i].LevelID ;
     dr["TimeType"] = p_ProductPriceArr[i].TimeType ;
     dr["TimeInt"] = p_ProductPriceArr[i].TimeInt ;
     if(p_ProductPriceArr[i].UnitPrice.Length<=0)
     {
      dr["UnitPrice"] = System.DBNull.Value;
     }
     else
     {
      dr["UnitPrice"] = p_ProductPriceArr[i].UnitPrice ;
     }
     ds.Tables[0].Rows.Add(dr);
    }
    sda.InsertCommand = new SqlCommand();
    sda.InsertCommand.Connection = conn;
    sda.DeleteCommand = new SqlCommand();
    sda.DeleteCommand.Connection = conn;

    sda.InsertCommand.CommandText = SQL_INSERT_ALL_PRODUCTPRICE;
    sda.DeleteCommand.CommandText = SQL_DELETE_ONE_PRODUCTPRICE;
    sda.InsertCommand.Parameters.Add(PARM_PID,SqlDbType.SmallInt,4,"PID");
    sda.DeleteCommand.Parameters.Add(PARM_PID,SqlDbType.SmallInt,4,"PID");
    sda.InsertCommand.Parameters.Add(PARM_LEVELID,SqlDbType.SmallInt,2,"LevelID");
    sda.InsertCommand.Parameters.Add(PARM_TIMETYEP,SqlDbType.Bit,1,"TimeType");
    sda.InsertCommand.Parameters.Add(PARM_TIMEINT,SqlDbType.SmallInt,2,"TimeInt");
    sda.InsertCommand.Parameters.Add(PARM_UNITPRICE,SqlDbType.VarChar,20,"UnitPrice");
    int Rint = 0;
    try
    {
     Rint = sda.Update(ds);
    }
    catch
    {
     //ds.Tables[0].RejectChanges();
    }
    if(Rint<=0)
    {ds.Tables[0].RejectChanges();}
    else
    {ds.Tables[0].AcceptChanges();}
    return Rint;
   }

ds中我先删除所有行...然后新增行...
sda.Update(ds);的时候抛出了异常,但是数据库中的所有行已经被删除了，新增的行没有成功。。
///update没有用事务控制吗？怎么解决这个问题?

异常信息:
System.Data.DBConcurrencyException: 并发冲突: DeleteCommand 影响 0 个记录。 at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping) at System.Data.Common.DbDataAdapter.Update(DataSet dataSet, String srcTable) at System.Data.Common.DbDataAdapter.Update(DataSet dataSet) at Booksir.Iagent.SQLServerDAL.ProductPriceDAL.EditProductPrice(ProductPriceModelCollection p_ProductPriceArr) in e:\iagent\project\sqlserverdal\productpricedal.cs:line 189 at Booksir.Iagent.BLL.ProductPriceBLL.EditProductPrice(ProductPriceModelCollection p_ProductPriceArr) in E:\Iagent\project\BLL\ProductPriceBLL.cs:line 75


不知道问题出在那里?或者有什么好的解决方案/////请牛人指教