Is this a safe/strong input sanitization function?

[Emilyzmz]

This is the sanitization function used in a book I recently learned from - Sams Teach Yourself Ajax, JavaScript, and PHP All in One.I've been using it on my own PHP site. Is it safe for real-world usage?\[code\]function sanitizestring($var){ $var = strip_tags($var); $var = htmlentities($var); $var = stripslashes($var); return mysql_real_escape_string($var);}\[/code\]