Often times a developer will want to pass a piece of information between pages on his website. While the most desirable method to do this is via a form, sometime this just isn’t possible. During these times, it’s time to turn to query strings.
Query strings are a bit of a confusing concept, mostly because of their name. If you ignore the terminology, it is just a way for you to pass information between pages on a website using the url. This is the key to Query strings. They make your url go from this
index.php
to this:
index.php?q1=something&q2=somethingelse
And that’s all a query string is. When a user sees a link like that in the location bar in their browser what they are really seeing is index.php but with a little added information passed to it.
How do you do it?
Creating query strings is ridiculously simple. Say you want to pass an id to news.php. You would like it like this:
<a href="index.php?id=4">Link to index.php with id 4</a>
If you wanted to pass an id and another value, you would do it like this:
<a href="index.php?id=4&another=value">Link to index.php with id 4 and another value</a>
And that’s it. If a user clicks on that link they will be directed to index.php with your query string attached!
How do I get that information?
Writing the query string, of course, is only half the battle. The other half is actually reading that query string. This is where the $_GET array comes into play. $_GET is built into PHP and provides you access to the values after the ? in query strings. Since $_GET is an array, the key that you will use to access your values, are their names!
A little confusing, but let me give you a quick breakdown using one of our query strings:
key = id
value = 4
So that means, to get that value 4, we would need to use $_GET['id'].
If we follow that logic, then to get the value of “another” we would use $_GET['another'].
Summary
Query strings are a little confusing until you realize that they’re just a way of passing variables through the url.
Still confused? Post your questions in the comments or send me an email!
