Coding to convert spreadsheet to csv in PHP
First you need to do is to convert your excel file from .xls or .xlsx to .csv format. With this procedure you can migrate large data from Excel to MySql database. In this link: http://php-drops.blogspot.in/2011/04/read-excel-sheet-xls-file-with-php.html you will find detailed explanation how to read .xls files with PHP. Also there is a source code that will help you.
Other way that you can do that is to go on this link: http://phpexcel.codeplex.com/ and use their php library for reading the .xls file. Then loop over cells and write to csv file the data.