C#

crMyCR cr = new crMyCR();
cr.SetDataSource(dt1);
cr.Subreports[0].SetDataSource(dt2);

private void btnExport_Click(object sender, EventArgs e)
        {
           
            SqlCeDataReader reader;
            SqlCeConnection conn = new SqlCeConnection(connStr);
           
           
          
            



                conn.Open();//open connection


                SqlCeCommand cmd = new SqlCeCommand("SELECT No, DateAndTime, LocationInformation FROM Location", conn);
                cmd.ExecuteNonQuery();

              
              
                 reader = cmd.ExecuteReader();

                
                //the "using" statement causes the close method to be called internally.
                //if "using" not used, use "writer.Close()" in try-catch-finally explicitly




                 using (StreamWriter writer = new StreamWriter("\\Program Files\\file.csv", true))
            { //false means: file is overwritten
                try
                {
                    while (reader.Read())
                    {
                        writer.Write(reader["No"]);
                        writer.Write("#");
                        writer.Write(reader["DateAndTime"]);
                        writer.Write("#");
                        writer.Write(reader["LocationInformation"]);
                        writer.WriteLine(); //next new line			
                    }//while 
                }
                catch (Exception excp)
                {
                    MessageBox.Show(excp.Message);
                }
                finally
                {
                   
                    reader.Close(); //close the reader
                    conn.Close();
                }//try-catch
            }//using  	  
            MessageBox.Show("Data of table writtten into \\Program Files\\file.csv file", "Writing completed");

         }