C#对文件的写下一定要用.flush()方法才行么

C#对文件的写入一定要用.flush()方法才行么？

       private void button2_Click(object sender, EventArgs e)

        {

            if (ofdExport.ShowDialog() != DialogResult.OK)

                return;

            using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDBFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True"))

            {

                conn.Open();

                using (SqlCommand cmd = conn.CreateCommand())

                {

                    cmd.CommandText = "select * from T_MyTable1";

                    using (FileStream fs1 = File.OpenWrite(ofdExport.FileName))

                    //using(FileStream fs = new FileStream("e:\\2.txt",FileMode.OpenOrCreate,FileAccess.Write))

                    {

                        StreamWriter sWrite = new StreamWriter(fs1);

                        //StreamWriter sWrite = new StreamWriter("e:\\2.txt", false, System.Text.Encoding.Default);

                        using (SqlDataReader reader = cmd.ExecuteReader())

                        {

                            while (reader.Read())

                            {

                                string name = reader.GetString(reader.GetOrdinal("Name"));

                                //MessageBox.Show(name);

                                int age = reader.GetInt32(reader.GetOrdinal("Age"));

                                //MessageBox.Show(age.ToString());

                                sWrite.WriteLine(name+"|"+age.ToString());

                                sWrite.Flush();

                            }

                            MessageBox.Show("OK");

                        }

                    }

                }

            }

        }

    }

}