OracleConnection oconn = new OracleConnection(GetConnString()); 
OracleDataAdapter oda = new OracleDataAdapter("select * from t1", oconn); 
DataTable dt1 = new DataTable(); 
oda.Fill(dt1); 

OracleConnection oconn1 = new OracleConnection(GetConnString()); 
oconn1.Open(); 
OracleDataAdapter oda1 = new OracleDataAdapter("select * from t2", oconn1); 
DataTable dt2 = new DataTable(); 
oda1.Fill(dt2); 

--更新資料
foreach( DataRow row in dt1.Rows)
 {
  try
 { 
   //import row :                  
 object [] row2 = row.ItemArray;
 dt2.BeginLoadData();
 dt2.LoadDataRow(row2, false);
 dt2.EndLoadData();
 }
 catch(Exception ex)
 {
   throw ex;
 }
}

OracleCommandBuilder ocb1 = new OracleCommandBuilder(oda1); 
oda1.Update(dt2); 
dt2.AcceptChanges(); 
oconn1.Close();