csharp復制DataTable修改某列的值

/// <summary>
      /// 塗聚文
      /// 2012-04-14
      /// </summary>
      /// <param name="table"></param>
      /// <returns></returns>
      static DataTable GetDecTable(DataTable table)
      {
          if (!object.Equals(table, null))//
          {
                   // foreach(DataRow myRow in thisTable.Rows){
                   //foreach(DataColumn myCol in thisTable.Columns){
                   //   Console.WriteLine(myRow[myCol]);
                   //}
 
              //DataTable tablecopy = table.Copy();
              DataTable tableDec=new DataTable();
              //tableDec = table.Copy();
              //得到列的名稱和數據類型
              //foreach (DataColumn column in table.Columns)
              //{
              //    tableDec.Columns.Add(column.ColumnName,column.DataType);
              //}
              //    foreach (DataColumn myCol in table.Columns)
              //    {
              //        if (myCol.ColumnName == "EmployeeNo")
              //        {
              //           // row[myCol]
              //        }
              //foreach (DataRow row in table.Rows) // Loop over the rows.
              //{
 
              //        //tableDec.Rows.Add(myRow[myCol])
              //    }
              //    string employeeNo = CryptographerUTF.GetDecryptString(row["EmployeeNo"].ToString());
              //    string employeeName = CryptographerUTF.GetDecryptString(row["EmployeeName"].ToString());
              //    tableDec.Rows.Add();
              //}
              
              //克隆表結構，數據記錄沒有填充
 
              //tableDec = table.Clone();
              
              //foreach (DataColumn gcol in datatable.Columns)
              //{
              //    if (gcol.ColumnName == "EmployeeNo")
              //    {
              //        //修改數據類型
 
              //        gcol.DataType = typeof(String);
              //    }
              //}
              //為新表填充數據
                  //foreach (DataRow row in tableDec.Rows)
                  //{
                  //    DataRow 個nr = datatable.NewRow();
                  //    nr["EmployeeName"] = row["EmployeeName"];
                  //    //修改記錄
 
                  //    nr["EmployeeNo"] = row["EmployeeNo"] .toString()";
 
                  //    nr["sex"] = row["sex"];
                  //    datatable.Rows.Add(nr);
                  //}
 
               //復制表結構和數據
               tableDec = table.Copy();
              //為改變指定列的數據
              foreach (DataRow row in tableDec.Rows)
              {
                  //修改記錄的值
 
                  row["EmployeeNo"] = CryptographerUTF.GetDecryptString(row["EmployeeNo"].ToString());
                  //修改記錄值
                  row["EmployeeName"] = CryptographerUTF.GetDecryptString(row["EmployeeName"].ToString());
 
              }
              
 
              return tableDec;
 
          }
          else
          {
              return null;
          }
      }