从数据库中把数据导出到txt文件（savefiledialog控件）

if (sfddata.ShowDialog() == DialogResult.OK)
{
using (SqlConnection conn = new SqlConnection())
{
//计数器
int count = 0;
conn.ConnectionString = @"Data Source=./SQLEXPRESS;AttachDBFilename=|DataDirectory|/persons.mdf;Integrated Security=True;User Instance=True";
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = "select * from T_persons";
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
string db_name = reader.GetString(reader.GetOrdinal("pname"));
int db_scores = reader.GetInt32(reader.GetOrdinal("pscores"));
File.AppendAllText(Path.GetFullPath(sfddata.FileName), db_name + "|" + db_scores + "/r/n");
count++;
}
MessageBox.Show(count + "行数据导出完成");
}
}
else
{
return;
}