In PHP, you also have to open a connection to the database before querying it - it isn't just "open" all the time. Your code should also include lines like these:
mysql_connect(hostname,username,password) or die("MySQL Connect Error:" .mysql_error());
mysql_select_db(databasename) or die("MySQL Select DB Error:" .mysql_error());
$sql = "CREATE TABLE tablename (name VARCHAR(16), surname VARCHAR(16))";
$result = mysql_query($sql);
Check out the mysql web site for more options.