PHP Query Strings

In this chapter you will learn:

1. Why do we need Query Strings
2. Example - create query string
3. Note for query string
4. Example - Access data in the query string

Description

Query strings are not limited to form data. A query string is a string stored in a URL, we can manually create a URL containing a query string in PHP script, then include the URL as a link within the displayed page.

Example

Here's a simple example that creates two variables, $firstName and $age, then creates a link in the displayed page that contains a query string to store the variable values:

<?PHP/*j a  va 2 s.co  m*/
      $firstName = "Jack"; 
      $age = "34"; 
      $queryString = "firstName=$firstName&amp;age=$age"; 
      echo '<a href="index.php?' . $queryString . '"> Find out more info</a>';   
?>

The code above generates the following result.

If the user then clicks this link, index.php is run, and the query string data (firstName=John & age=34 ) is passed to the index.php script. Data has been transmitted from one script execution to the next.

Note

Note that the ampersand (&) character needs to be encoded as & inside XHTML markup.

Example 2

To access the field names and values in a query string, read them from the $_GET superglobal array.

$firstName = $_GET["firstName"]; 
$homePage = $_GET["homePage"];  

So it's easy to write a simple version of the index.php script referenced in the previous example:

<?php //  ja v  a2 s  .  c  o  m
   $firstName = $_GET["firstName"];   
   $homePage = $_GET["homePage"]; 
   $favoriteSport = $_GET["favoriteSport"]; 

   echo "$firstName \n"; 
   echo "$homePage \n"; 
   echo "$favoriteSport \n"; 
?>  

Next chapter...

What you will learn in the next chapter:

1. What is a cookie
2. Lifespan for a cookie
3. Note for cookie

PHP Query Strings