//多表多行多列的情况
foreach   (DataTable   dt   in   YourDataset.Tables)   //遍历所有的datatable
  {  
      foreach   (DataRow   dr   in   dt.Rows)   ///遍历所有的行
          foreach   (DataColumn   dc   in   dt.Columns)   //遍历所有的列
                Console.WriteLine("{0},   {1},   {2}",   dt.TableName,  dc.ColumnName,   dr[dc]);   //表名,列名,单元格数据
  }
//遍历一个表多行多列
  foreach(DataRow   mDr   in   dataSet.Tables[0].Rows   )  
  {  
       foreach(DataColumn   mDc   in   dataSet.Tables[0].Columns)  
      {  
                Console.WriteLine(mDr[mDc].ToString());    
       }  
  }
//遍历一个表多行一列
foreach(DataRow   row   in   DataSet1.Tables[0].Rows)  
  {  
            Console.WriteLine(row[0].ToString());  
  }
//一行一列
ds.Tables[0].Rows[0]["字段"]