Migration from MySQL to MS-SQL Server

Hi List, I want to re-implement a PHP-driven package named ATutor (http://atutor.ca) to work with MS-SQL Server. Currently, it works with MySQL. Unfortunately, authors of "ATutor" have not defined a class for database connectivity. In other words, they call each mysql functions directly in their code. It seems that I must change every line of code to make ATutor work with MS-SQL Server. 1) Is it suffice to replace every "mysql_FUNCTION" with "mssql__FUNCTION" in the code? I realized that most of MSSQL functions are very similar to MySQL functions, but their prefixes are different. (I should kindly thank the PHP Development Team for this) 2) I have not worked with MS-SQL Server before. Is there anything else which I should keep in mind? Thank you in advance, Behzad