Advanced Ajax Articles
1: Ajax Javascript Lessons
If you want to update a non form element, be sure to use the innerHTML attribute that is associated with all HTML elements. In our case we are updating a div every time a query is sent off. Also, remember that you can easily access an HTML element by giving it an id and using Javascript's document.getElementById function.
2: Quick Ajax Recap
So far we have created a new MySQL table, written a new PHP script and updated order.html twice. If you have followed the directions in the Ajax MySQL lesson and created the MySQL table ajax_example and ajax-example.php script then the updated order.html page will function like our example below.
3: Updating order.html
We have completed our initial order.html and ajax-example.php setup, now we just need our order.html page to update correctly when a query is returned. We'll be using a couple advanced Javascript functions to update a segment of order.html with the MySQL result display_string.
4: Create ajax-example.php Script
We already changed the destination URL in our ajaxRequest.open method, now we need to make a script to grab those variables from the query string and execute a MySQL Query. We're also going to use a special function mysql_real_escape_string to prevent any harmful user input from doing something they aren't supposed to (we're going to take steps against SQL Injection).
5: Passing Variables via Query String
A query string is a way of passing information by appending data onto the URL. You may have often seen it on the web, it's all the information that appears after a question mark "?". When you submit a form using GET it builds a query string, all we're doing here is manually building our own.
6: Create the MySQL Table
To clearly illustrate how easy it is to access information from a database using Ajax, we are going to build MySQL queries on the fly and display the results on "order.html".
7: MySQL Database
We already know how to run an external PHP script with AJAX, so let's take it to the next level and pull some data down from a MySQL database. Our "order.html" file and PHP script will have to be updated and we also need to make a new database.
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