Use button to change PHP variable

[PHPstarter]

Was wondering how to do this?

It's basically for a database table, so the button can be used to sort the results as ascending/descending.

Googled a bit, but there wasn't much on it as I could see.
Thanks

[Markus]

To change a server-side variable (in this case, PHP) from the client-side (browser), you generally pass a parameter in the URL of the page indicating the value. See the following:

<?php
 
/** To obtain values from the URL, use the super-global GET array.
if (isset($_GET['order']) && strlen($_GET['order']) > 0) {
    $order = $_GET['order']; // Read: SQL Injection
} else {
    $order = "asc"; // Default to ascending.
}
 
printf("Selected order: %s", $order);
 

If you're going to be using data that can be manipulated by the user in a database query, read up on SQL Injection.

[PHPstarter]

Many thanks for the reply, will go ahead and test it out =)

[kovik]

Generally, empty() is the accepted way of performing both "isset()" and "strlen() > 0" at the same time.

Also, since there are only two valid states of the query variable ("desc" and "asc"), it is considered more proper to treat is as a boolean (i.e. isdescending). Then you'd send the integer value 1 or 0 corresponding to true or false, respectively. This allows you to forcefully typecast the $_GET data to an integer, thus avoiding any SQL injection dangers.


When you are using pagination (separating database data into pages) via server-side queries, then using a query variable for your database query is the best route. However, if you are retrieving all of the data items at once, then JavaScript may be a better choice to reduce page loads and database queries. Though, if you are unfamiliar with JavaScript and not interested in learning it yet, then stick with PHP.

[PHPstarter]

Thanks for the detailed post, I'm gonna explore it and see how I can make this work as well :)

thanks again