php+mysql问题`

Question

用PHP   
mysql_connect不能连接数据库，
数据库MYSQL已启动，
mysql_connect("localhost","root");
可以在DOS下用mysql,

Answer 1

<?
$db = mysql_connect("localhost","root","");
mysql_select_db("mydb",$db);
$result = mysql_query("SELECT fullname FROM employees",$db);
printf("name :%s<br>\n",mysql_result($result,0,"fullname"));
?>

Answer 2

<?
$db = mysql_connect("localhost","root","");
mysql_select_db("mydb",$db);
$result = mysql_query("SELECT fullname FROM employees",$db);
printf("name :%s<br>\n",mysql_result($result,0,"fullname"));
?>
连接不到数据库
系统是：win98,pws,php4,mysql,