I have always wondered how to use php to recall a specific article. On a lot of pages you see .php?id=3 or .php?article=Article-Name-Here and I am just curious as to how to use this.

Does this tell the php script to look in the database for the id table then go to record #3? Or does it tell the script to look within a certain table that has an id field with a record of 3?

It's much simpler than that. Anything after a ? that you see in the URL is where variables that are passed to a server-side PHP (or Perl, or ASP, etc.) script. Variables in the URL are called GET variables. The two ways to pass variables to a server-side script, like PHP, are through POST and GET.

Variables in the URL (GET variables) are separated by &. So, if the URL was something like:

http://www.example.com/page.php?foo=hello&bar=world

This would pass the two variables foo and bar to the server-side script page.php, where foo would be equal to hello and bar would be equal to world.

So, to answer your question, they would use a GET variable such as id to pass a number or word to the server telling it what page to display.

I've used this on a site I built, go to http://darcrobotics.org/index.php?p=about and you will see that its content is different than if you go to a page with a different variable, for example http://darcrobotics.org/index.php?p=home

There's a tutorial on POST and GET variables in PHP here: http://www.tizag.com/phpT/postget.php

Hope this helps!
~Trey

its your input to your script (input for id, can be anything the script specifies, id just means the script requires input id).

My primary key in my database is id for the products table (as it is with all of my tables.) The id field is auto-increment so that each product has a unique id.

Here is my products table showing 4 different fields (there are a total of 16 fields total in this table)

http://ingramswaterandair.com/db_testing/

As you can see, each product has its own id. if I wanted to view the information for say the product with the id 9, how would I go about doing this?

It is a simple question, but I'm guessing it is a complex answer. Adding index.php?id=9 to the end of the url just refreshes the page.

I would like to create a page that had the products listed on them, then when you click on the link it would show the product.

EDIT: This would make it much easier, as if I had a page with 2747 products on it, I could just make the url "index.php?id=".$row={'id'} to display the correct image.

you can use index.php or you can create a page called product.php you'll need a db connection first then you can do this

PHP Code:

if (isset($_GET['id']) && is_numeric($_GET['id'])) {
    $get_product = "SELECT * FROM product_table WHERE id='$_GET[id]'";
    
    $product = mysql_fetch_assoc(mysql_query($get_product));
    
    echo $product['product_name'];
    echo $product['product_desc'];
} else {
    echo 'Please Select Product';
} 


Simply modify your query based on GET:

PHP Code:

$dbSQL  = "SELECT * FROM stuff";
$dbSQL .= !empty($_GET['id']) ? " WHERE id = ".$_GET['id'] : null; 


Then check your row count and act accordingly:

PHP Code:

if (mysql_num_rows($recordset_object) > 1)
 {
  // ## show the product list
 }
else
 {
  // ## show the selected product
 } 


Ah I understand now. Basically it is an if/else statement that says...

If there has not been a product selected then show the product list.

If there has been a product selected, then show the product information.

And this can only be accomplished with the GET method because it passes the variables through the URL.

Therefore if I added this code and there was only 1 returned value for ID (such as index.php?id=9) then it would show that product.

Then if I wanted to break it down even more for something like specifications on that product I could add another if/else statement and have the url be something like...

specifications.php?id=9 or something like this that would only display the specification information rather than the price and everything else.

I believe I understand now. I will try to get it working, if not I may be back to ask more questions.

Brandon

Thank you guys. I got this working. You can take a look at it at http://www.ingramswaterandair.com/db_testing

This is exactly what I was wanting to figure out.