1. Web Systems Development (CSC-215)
Lecture 11: Query Strings
Wednesday 14th March 2018

2. Saving State
Most of the scripts we have done up to now have had significance for single instances
After the scripts are run, removed from web server's memory

3. Saving State
Data needs to be saved in between browser request, when, for example,
You need to keep track of items in a shopping cart
To keep track of a user posting comments in forums
Not just logged in users, state for returning users
...

4. Need to preserve state of user interaction

5. Saving State
Query strings
Cookies
HTTP authentication
Sessions

6. Query Strings
Quick convenient way to pass small amounts of data between browser requests
Example: keywords entered in a search function
Only use in situations where sending incorrect data won't compromise security

9. Building Query Strings
A query string is simply a string of characters stored in a URL
Manually create a URL containing a query string in PHP script, then include the URL as a link within the displayed page or in an , for example
PHP even provides some built - in functions to make the process easier

11. Query strings only allow specific characters, so use urlencode() to include exceptions

13. Accessing Data

14. Accessing Data

15. example

18. Pagination
Uses query strings to create previous and next page links

22. Lecture content adapted from chapter 13 of Learning PHP, MySQL, JavaScript, CSS & HTML5 & chapter 10 of Beginning PHP 5.3