3 way convert data to excel with php

1. http://avenir.ro/codeigniter-how-to-export-data-to-excel-file/
2. http://www.anomalous.co.za/export-database-data-excel-codeigniter-and-phpexcel/
3. http://shashilakshan.blogspot.com/2013/09/codeigniter-write-data-into-excel.html or http://www.genuinescope.com/blog/codeigniter-write-data-into-excel-without-using-any-plugin/