Need a php script to insert variables into results from database query returning a blob field.

I need a php script that will insert variables in the results from a database query returning a blob field. I have the script <?php include("[login to view URL]"); $firstname="John"; $lastname="Smith"; $query="SELECT msg FROM messages WHERE mid='1'"; $result=mysql_query($query); $query_data=mysql_fetch_array($result); $msg=$query_data[0]; echo $msg; ?> $msg reads Hello $firstname $lastname and it is echoing Hello $firstname $lastname instead of Hello John Smith Which is what I need it to do.