Thanks Loganix for your response..   I am using Datatble in the follwing way  

OracleDataAdapter da = new OracleDataAdapter(cmd);
                DataTable dt = new DataTable("MyResults");
                da.Fill(dt);

Is the above code correct

How can I use this datable to  read the values  because i print them on the excel...

So now i have to loop through the Datable to read as well as export to excel,is it not...How would i do that...Something like below...

 foreach (DataRow dr in dt.Rows)
                {

                  TotalPopulation = Convert.ToInt32(dt.Rows[0]["Population"]); 

}

Thank you