We have the code required to retrieve the item information from the database.

It's time to use those results to display our media items.

Unfortunately, changing the site to use a database instead of a simple array

is going to require us to rewrite everything from scratch.

Gotcha, actually it's not,

the original data.php file contains an array of catalog information.

All we need to do is update that file

to pull the catalog information from the database instead.

After that we can start updating our functions to make

better use of the data from the database.

In the functions file we have the code for

manipulating the catalog information and adding it to our site.

The data.php file contains the data itself.

This is an example of the programming concept known as separating concerns.

As you do more programming, you'll hear more and

more about the concept of separating concerns.

One of the main benefits of separating concerns is that you can make

major changes in one area, without having any effect on the other areas.

For our listing pages, we separate our concerns so

that all we have to change is our data file.

>> Back in the workspace associated with this video, let's change data.php.

By changing this file we won't have to rewrite any of the path to our includes.

Will include the connection.php file and

then we'll comment out the rest of this code.

This will leave it here for reference.

Now let's go back to connection.php.

Our code creates a pdo object that connects to the database.

It runs a query against that database and

displays the result set as an array to the screen.

Let's change this last line, so that instead of displaying the results

to the screen it loads it into a variable called catalog.

The original array of catalog information,

was also stored in a variable name catalog.

So by storing the results of our database query in the same variable

our original code will still work.

Now let's go take a look at the home page.

It looks exactly as it did, which is good.

We haven't made any changes to the function of the code.

All we're doing is generating the catalog array from the database using pdo.

If I click on Books in the navigation, we'll see our Books page, Movies,

Music and our Full Catalog.

All of those pages currently call functions that in turn

use the catalog array.

We were able to change the source of the data displayed on these pages

by simply putting the results of our database query into a catalog array,

instead of recreating that array manually.

Just to make sure that we're using the database,

let's change our connection string to break the connection.

If our code is working properly, this will show an error message.

This looks right.

Our site is using our code that connects to the database and

when the string is wrong, we're getting the error message.

Let's change that back.

And everything looks good.

>> Before we move on.

I want to point out that we will be improving the performance

on some of these pages shortly.

Currently our code retrieves all the items in the catalog.

This makes our code do extra unnecessary work.

For example to display only the books in the catalog.

The code retrieves the entire catalog, books, music and movies,

then loops through the entire catalog to display just the books.

This type of filtering is the type of work at which databases excel.

We'll eventually write additional queries to make our database handle that load.

And in turn, this makes our site faster.

Before we're done with this project, we're going to set up multiple functions and

multiple queries to the database to pull specific data,

instead of the entire catalog.

But before we do that,

let's modify the code we just pasted to make things cleaner and easier to reuse.