Generate an Output Based on Form Options - php

Question

I've searched this relentlessly and I cannot find an answer to my quandary - I think the problem is that I'm not exactly sure WHAT to search for! Anyhow, my problem is this...
Scenario:
Imagine having a database of, for arguments sake, recipes and you wanted to give users the ability to generate a list of recipe suggestions based on various criteria.
In the form of a web page, I would want this to be a series of drop down boxes on the left. The user would select their filter options from the drop down boxes and, after pressing the submit button, would be presented with a list of recipes that fit the criteria.
So they could, for example select 'Meal Type', 'Calories', 'Cooking Time' and then (after hitting submit) get back a list of recipe suggestions that fit the bill.
(Ideally they would appear without the need for reloading the page and would be contained within a slider to browse through, but I can probably crack that part if I get the underlying part sorted...)
Requirement:
I just need to know - at a top level - which technologies I would use to achieve this (and the process of how they work together).
I'm guessing I'd need a MySQL dB with recipes that are tagged with criteria, then use the form and php to pull from the database. Is this correct?!
Seems like such a common requirement, but I can find no good reading on how to achieve this..

Answer 1

Take a look at the PHP guide to prepared statements. You'll be basically writing a select statement against the table where your data resides, with the where clause of the select statement being the parameters selected by your user in the form.
PHP Prepared Statements
The reason you want to stick to prepared statements is that they are generally more secure against attacks on your site via the form, using SQL injection.
For the end to end solution, your front end will submit to a PHP page which will then handle the criteria specified by the user, translating those into the prepared statement which will find the data from your table. The table itself will need to have columns which correspond to the criteria. That gets more into database design which is a much larger topic to cover here, however there are plenty of guides out there for that.
Really you want to break the solution down into the subcomponents, then find various guides out there to tackle the parts. Good luck, hope this helps. :)

Answer 2

The process:
1) User makes selection and clicks submit button. That will initiate a HTTP POST to a PHP page (can be the same PHP page) where you would collect these information.
2) Open a MySql database connection with PHP. You would need to know SQL to pull data from MySql DB. Depending on how your database schema is laid out.
3) Once you pull this information display them as a checkbox where user can click.
This is the bare minimum.
If you wanna get a bit more fancy you can use JQuery ajax post (http://api.jquery.com/jQuery.post/) so the page does not refresh.
Good luck and I'm already hungry. haha.

Answer 3

When the user selects options in your form and submits it, this will run a PHP script on the server. The server retrieves the option parameters, and uses them to construct a SQL query. For instance, the script might contain something like:
$criteria = array();
if (isset($_POST['calories'])) {
$criteria[] = 'calories < '.$_POST['calories']);
}
if (isset($_POST['time'])) {
$criteria[] = 'cooking_time < '.$_POST['time']);
}
...
$query = 'SELECT * FROM recipes WHERE '.implode(' AND ', $criteria);
You use a library like mysqli or PDO to perform the query and get the results. Then you loop through the results, and format them into an HTML table which will be returned to the user as the resulting web page.
Or the PHP script could return the results as JSON data. Your web page could use AJAX to get this data from the server, then use JavaScript to format it into a table.