get method in the query string

[stu]

Hi

I have been trying to write a simple script that can retrive products from the database on the index.php page and then pass these via the query string to show the product details on the items page item.php. I want to use one item.php page to show the details. I know this can be done but i'm not sure how. I have tried reading up on this but not getting very far. I have wrote roughly what i have. I wounder if someone could help me a little. Once i have the basic principle i will be able to modify the rest to meet my needs but i do need to get the basics working first.

Thank you in advance for your help.


Index.php

// This is the main page that will call the products name and id from the database table.


<?php
// Create the connection and select the DB
$link = mysql_connect("localhost","username","password");

if ($link) {
   mysql_selectdb("database",$link);
    }

$qry = "SELECT * FROM products ORDER BY name";
$result=mysql_query($qry);
while ($newArray = mysql_fetch_array($result)) {
$id = $newArray['id'];
$name = $newArray[name];
echo "<a href='item.php?$id'>$name</a>";
echo "<br />";
}
?>

// the above code should now list the products in the database in name order
// this should look like this in the page
// product 1
// product 2
// product 3
// each product will be a link to the item.php page and contain the product id in the query string

item.php


// this page would now be the page to can use the item id that has been passed in the query string to find the
// product information from the database

<?php
// Create the connection and select the DB
$link = mysql_connect("localhost","username","password");

if ($link) {
   mysql_selectdb("database",$link);
    }

$result = mysql_query("SELECT id, name, price FROM products WHERE id='id passed via query string'");
if (!$result) {
    echo 'Could not run query: ' . mysql_error();
    exit;
}
$row = mysql_fetch_row($result);   

echo"$row[0]";
echo "<br />";
echo "$row[1];
echo "<br />";
echo "row[2]";

?>


thats the code i have so far how do i get the product id form the query string? I know this can be done

[Andy]

Hi Stu,

you should assign an array key to the value that you pass in the query string (don't just pass a value). This is good coding practice I think.

So in your index page code have:

Code:

echo "<a href='item.php?pid=$id'>$name</a>";

Here I have added the key "pid" which helps me recognise that it refers to a Product ID.

Then in your item.php code you retrieve the PID as follows:

Code:

$pid = $_GET['pid'];
if (!isset($pid)) die("No product ID was specified!");
$pid = (int) $pid; // Force the ID value to a type of Integer to avoid problems of SQL injection attacks

The query string values are placed into a global array called $_GET. And in PHP, an array is an associative array comprised of key->value pairs so it's best to specify a key in this case for easy coding and easy debugging.

[Andy]

p.s. here is a cool way to display the contents of an array when you are debugging PHP scripts:

Code:

<pre>
<?php
print_r($a);
?>
</pre>

This HTML + PHP code prints out the contents of the array $a to the web page. But delete the code from your site as soon as you finish debugging.

[stu]

Hi


Thank you very much, works a treat, Now looking back at the scripts that were sort of showing this i understand them. Its always they way,

Again thank you.

[Andy]

No problem 

Very often, a tiny thing can hold us back from major progress!

[stu]

Hi

Is there a way to pass two varibales in the query string?

i've tried a few ways but none seem to work, I think its ment to be like this

echo "<a href='item.php?pid=$id;cat=toys'>$name</a>";

then added the extra line on the item page to retrive the value (line 2)

$pid = $_GET['pid'];
$cat = $_GET['cat'];
if (!isset($pid)) die("No product ID was specified!");
$pid = (int) $pid; // Force the ID value to a type of Integer to avoid problems of SQL injection attacks


sorry to be a pain.

thanks

[Andy]

Code:

echo "<a href='item.php?pid=$id&cat=toys'>$name</a>";

Use an ampersand character to separate the items.