no database selected

[admin]

my php page show "No database selected"
and the code is below.
help me please.
<?
$database="shopping";
$hostname="ihsan";
$username="user";
$password="";
if (!$dbh=mysql_connect($hostname,$username,$password))
{
echo mysql_error();
exit();
}
mysql_select_db($database,$dbh);
$sql="select type, name, image_path from category_types";
if(!$res=mysql_query($sql,$dbh))
{
echo mysql_error();
exit();
}
while($row=mysql_fetch_row($res))
{
echo "<tr>";
echo "<td><img src=http://www.phpbuilder.com/board/archive/index.php/$row[2]>";
echo "<td><a href=category.php?type=$row[0]>$row[1]</a>";
}
?>