/// param name="table">准备更新的DataTable新数据/param>
  /// param name="TableName">对应要更新的数据库表名/param>
  /// param name="primaryKeyName">对应要更新的数据库表的主键名/param>
  /// param name="columnsName">对应要更新的列的列名集合/param>
  /// param name="limitColumns">需要在ＳＱＬ的ＷＨＥＲＥ条件中限定的条件字符串，可为空。/param>
  /// param name="onceUpdateNumber">每次往返处理的行数/param>
  /// returns>返回更新的行数/returns>
  public static int Update(DataTable table, string TableName, string primaryKeyName, string[] columnsName, string limitWhere,int onceUpdateNumber)
  {
    if (string.IsNullOrEmpty(TableName)) return 0;
    if (string.IsNullOrEmpty(primaryKeyName)) return 0;
    if (columnsName == null || columnsName.Length = 0) return 0;
    DataSet ds = new DataSet();
    ds.Tables.Add(table);
    int result = 0;
    using (SqlConnection sqlconn = new SqlConnection(SqlHelper.ConnString))
    {
      sqlconn.Open();

      //使用加强读写锁事务  
      SqlTransaction tran = sqlconn.BeginTransaction(IsolationLevel.ReadCommitted);
      try
      {
        foreach (DataRow dr in ds.Tables[0].Rows)
        {
          //所有行设为修改状态  
          dr.SetModified();
        }
        //为Adapter定位目标表  
        SqlCommand cmd = new SqlCommand(string.Format("select * from {0} where {1}", TableName,limitWhere), sqlconn, tran);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        SqlCommandBuilder sqlCmdBuilder = new SqlCommandBuilder(da);
        da.AcceptChangesDuringUpdate = false;
        string columnsUpdateSql = "";
        SqlParameter[] paras = new SqlParameter[columnsName.Length];
        //需要更新的列设置参数是,参数名为"@+列名"
        for (int i = 0; i  columnsName.Length; i++)
        {
          //此处拼接要更新的列名及其参数值
          columnsUpdateSql += ("[" + columnsName[i] + "]" + "=@" + columnsName[i] + ",");
          paras[i] = new SqlParameter("@" + columnsName[i], columnsName[i]);
        }
        if (!string.IsNullOrEmpty(columnsUpdateSql))
        {
          //此处去掉拼接处最后一个","
          columnsUpdateSql = columnsUpdateSql.Remove(columnsUpdateSql.Length - 1);
        }
        //此处生成where条件语句
        string limitSql = ("[" + primaryKeyName + "]" + "=@" + primaryKeyName);
        SqlCommand updateCmd = new SqlCommand(string.Format(" UPDATE [{0}] SET {1} WHERE {2} ", TableName, columnsUpdateSql, limitSql));
        //不修改源DataTable  
        updateCmd.UpdatedRowSource = UpdateRowSource.None;
        da.UpdateCommand = updateCmd;
        da.UpdateCommand.Parameters.AddRange(paras);
        da.UpdateCommand.Parameters.Add("@" + primaryKeyName, primaryKeyName);
        //每次往返处理的行数
        da.UpdateBatchSize = onceUpdateNumber;
        result = da.Update(ds,TableName);
        ds.AcceptChanges();
        tran.Commit();

      }
      catch
      {
        tran.Rollback();
      }
      finally
      {
        sqlconn.Dispose();
        sqlconn.Close();
      }


    }
    return result;
  }