I am not sure what actually you wanna do but hope fully this may help,
1st problem: localhost is not in "" (quots)
that should be like this
mysql_connect("localhost",$username,$password);
2nd:
<input name = "date" value="<? echo $row['date']; ?>" type="text" /> is out side of loop so that $row have no value in it
see this, this will print multiple(according to the database records)input fields with date values in it
<?php
$username="root";
$password="";
$database="dbdate";
mysql_connect('localhost',$username,$password);
@mysql_select_db($database) or die("Unable to select database");
$query = "SELECT *
FROM `cdate`
WHERE 1
LIMIT 0 , 30";
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)) {
//echo $row['date'];
echo "<input name = \"date\" value=\"" . $row['date'] . "\" type=\"text\" /> <br /> <br />";
}
?>
or
<?php
$username="root";
$password="";
$database="dbdate";
mysql_connect('localhost',$username,$password);
@mysql_select_db($database) or die("Unable to select database");
$query = "SELECT *
FROM `cdate`
WHERE 1
LIMIT 0 , 30";
$result = mysql_query($query) or die(mysql_error());
$row = mysql_fetch_array($result)
?>
<input name = "date" value="<?php echo $row['date']; ?>" type="text" />