两个table中行的互换

      if(ds_all.Tables.Count<1)
      {
       ds_all=Pma.GetAttachmentInfo(ds_docno.Tables[0].Rows[i]["DocNo"].ToString(),"EDCC"); 
      }
      else
      {
       DataSet ds =new DataSet();
       ds=Pma.GetAttachmentInfo(ds_docno.Tables[0].Rows[i]["DocNo"].ToString(),"EDCC");
       if(ds.Tables.Count>0)
       {
        //DataRow dr=ds.Tables[0].NewRow();
        //if(ds==null)
        for(int j=0;j<ds.Tables[0].Rows.Count;j++)
        {
         ds_all.Tables[0].ImportRow(ds.Tables[0].Rows[j]); //两个table中行的互换；
        }     
       }
      
      }
     }