Integrating Database Results

We have the code required to retrieve the item information from the database. 0:00 It's time to use those results to display our media items. 0:04 Unfortunately, changing the site to use a database instead of a simple array 0:08 is going to require us to rewrite everything from scratch. 0:13 Gotcha, actually it's not, 0:17 the original data.php file contains an array of catalog information. 0:19 All we need to do is update that file 0:25 to pull the catalog information from the database instead. 0:28 After that we can start updating our functions to make 0:32 better use of the data from the database. 0:35 In the functions file we have the code for 0:38 manipulating the catalog information and adding it to our site. 0:40 The data.php file contains the data itself. 0:44 This is an example of the programming concept known as separating concerns. 0:48 As you do more programming, you'll hear more and 0:53 more about the concept of separating concerns. 0:55 One of the main benefits of separating concerns is that you can make 0:58 major changes in one area, without having any effect on the other areas. 1:02 For our listing pages, we separate our concerns so 1:08 that all we have to change is our data file. 1:11 >> Back in the workspace associated with this video, let's change data.php. 1:14 By changing this file we won't have to rewrite any of the path to our includes. 1:20 Will include the connection.php file and 1:24 then we'll comment out the rest of this code. 1:29 This will leave it here for reference. 1:38 Now let's go back to connection.php. 1:40 Our code creates a pdo object that connects to the database. 1:44 It runs a query against that database and 1:48 displays the result set as an array to the screen. 1:50 Let's change this last line, so that instead of displaying the results 1:54 to the screen it loads it into a variable called catalog. 1:58 The original array of catalog information, 2:05 was also stored in a variable name catalog. 2:07 So by storing the results of our database query in the same variable 2:10 our original code will still work. 2:14 Now let's go take a look at the home page. 2:16 It looks exactly as it did, which is good. 2:19 We haven't made any changes to the function of the code. 2:22 All we're doing is generating the catalog array from the database using pdo. 2:25 If I click on Books in the navigation, we'll see our Books page, Movies, 2:30 Music and our Full Catalog. 2:35 All of those pages currently call functions that in turn 2:39 use the catalog array. 2:42 We were able to change the source of the data displayed on these pages 2:44 by simply putting the results of our database query into a catalog array, 2:48 instead of recreating that array manually. 2:52 Just to make sure that we're using the database, 2:55 let's change our connection string to break the connection. 2:57 If our code is working properly, this will show an error message. 3:06 This looks right. 3:09 Our site is using our code that connects to the database and 3:10 when the string is wrong, we're getting the error message. 3:13 Let's change that back. 3:16 And everything looks good. 3:21 >> Before we move on. 3:24 I want to point out that we will be improving the performance 3:25 on some of these pages shortly. 3:28 Currently our code retrieves all the items in the catalog. 3:30 This makes our code do extra unnecessary work. 3:34 For example to display only the books in the catalog. 3:38 The code retrieves the entire catalog, books, music and movies, 3:41 then loops through the entire catalog to display just the books. 3:46 This type of filtering is the type of work at which databases excel. 3:52 We'll eventually write additional queries to make our database handle that load. 3:57 And in turn, this makes our site faster. 4:02 Before we're done with this project, we're going to set up multiple functions and 4:05 multiple queries to the database to pull specific data, 4:09 instead of the entire catalog. 4:12 But before we do that, 4:14 let's modify the code we just pasted to make things cleaner and easier to reuse. 4:16