php & mysql

his is a short article which shows you how to make a simple guestbook by capturing the visitor’s input and storing the data in a database using PHP. You’ll need to know a bit of HTML, PHP and MySQL in order to do the task. For a guestbook to work, we’ll need to create 3 pages.

1. We’ll need a form to prompt the visitor to leave a comment in your guestbook. Let’s call this page comments.php .
2. We’ll need to create some PHP and MySQL code to capture the visitor’s input and save it to the database. Let’s call this page store_comment.php.
3. Finally, More >

During Rasmus’s talk last week at the php|works conference, he showed how easy it is to parse XML in PHP 5, using simpleXML. In his example, he used the Flickr public photo RSS feed, to parse and output. A lot of people don’t know about this feed, which gets updated the moment a new photo gets uploaded. Furthermore, a lot of people upload their personal photos, and make them private after their uploaded. Click here to see it in action. Here are the 2 lines of code:

<?php
    $url = 'http://www.flickr.com/services/feeds/photos_public.gne';
    foreach(simplexml_load_file($url)->entry as $it) echo $it->content;
?>

Be sure to mark you More >

A lot of companies these days (including Amazon and Yahoo!) are exposing their web services in the form of REST resources. At a high level REST is pretty easy to understand, all you’re doing is exposing a web service in the form of a URL. Users can then query this URL, through HTTP methods like GET and POST. REST calls generally return some type of XML or Object Encoding like JSON.

An example would be Yahoo!’s Geocoding API, with the following URL:

http://api.local.yahoo.com/MapsService/V1/geocode?appid=YahooDemo&street=701+First+Street&city=Sunnyvale&state=CA

I would get:

<Result precision="address">
   <Latitude>37.416384</Latitude>
   <Longitude>-122.024853</Longitude>
   <Address>701 FIRST AVE</Address>
   <City>SUNNYVALE</City>
   <State>CA</State>
   <Zip>94089-1019</Zip>
   <Country>US</Country>
</Result>

So Yahoo! exposes the Geocode URL More >

If you don’t know the difference between using double quotes or single quotes when using Strings in PHP, you should. The PHP Manual page for Strings covers all this, but basically strings created with double quotes will be parsed by PHP. This example shows what I mean:

// they both output 'Yahoo Google'
$str = 'Google';
echo 'Yahoo' . $str;
echo "Yahoo $str";

At first glance you might think, who cares? The key note is deep in the manual page:

Parsing variables within strings uses more memory than string concatenation. When writing a PHP script in which memory usage is a concern, consider using More >

There’s a lot of examples on the internet about creating and using the singleton pattern within your application. From the PHP Docs:

The Singleton pattern applies to situations in which there needs to be a single instance of a class. The most common example of this is a database connection. Implementing this pattern allows a programmer to make this single instance easily accessible by many other objects.

Within any class you want to have use the singleton pattern, just add a getInstance method, like I have in the Obj code listing below. To access that instance use the scope resolution operator:

$obj = More >