---
isChild: true
title:   Interacting with Databases
anchor:  databases_interacting
---

## Interacting with Databases {#databases_interacting_title}

When developers first start to learn PHP, they often end up mixing their database interaction up with their
presentation logic, using code that might look like this:

{% highlight php %}
<ul>
<?php
foreach ($db->query('SELECT * FROM table') as $row) {
    echo "<li>".$row['field1']." - ".$row['field1']."</li>";
}
?>
</ul>
{% endhighlight %}

This is bad practice for all sorts of reasons, mainly that it's hard to debug, hard to test, hard to read and it is
going to output a lot of fields if you don't put a limit on there.

While there are many other solutions to doing this - depending on if you prefer [OOP](/#object-oriented-programming) or
[functional programming](/#functional-programming) - there must be some element of separation.

Consider the most basic step:

{% highlight php %}
<?php
function getAllFoos($db) {
    return $db->query('SELECT * FROM table');
}

$results = getAllFoos($db);
foreach ($results as $row) {
    echo "<li>".$row['field1']." - ".$row['field1']."</li>"; // BAD!!
}
{% endhighlight %}

That is a good start. Put those two items in two different files and you've got some clean separation.

Create a class to place that method in and you have a "Model". Create a simple `.php` file to put the presentation
logic in and you have a "View", which is very nearly [MVC] - a common OOP architecture for most
[frameworks](/#frameworks).

**foo.php**

{% highlight php %}
<?php
$db = new PDO('mysql:host=localhost;dbname=testdb;charset=utf8mb4', 'username', 'password');

// Make your model available
include 'models/FooModel.php';

// Create an instance
$fooModel = new FooModel($db);
// Get the list of Foos
$fooList = $fooModel->getAllFoos();

// Show the view
include 'views/foo-list.php';
{% endhighlight %}


**models/FooModel.php**

{% highlight php %}
<?php
class FooModel
{
    public function __construct(protected PDO $db)
    {
    }

    public function getAllFoos() {
        return $this->db->query('SELECT * FROM table');
    }
}
{% endhighlight %}

**views/foo-list.php**

{% highlight php %}
<?php foreach ($fooList as $row): ?>
    <li><?= $row['field1'] ?> - <?= $row['field1'] ?></li>
<?php endforeach ?>
{% endhighlight %}

This is essentially the same as what most modern frameworks are doing, albeit a little more manual. You might not
need to do all of that every time, but mixing together too much presentation logic and database interaction can be a
real problem if you ever want to [unit-test](/#unit-testing) your application.


[MVC]: https://code.tutsplus.com/tutorials/mvc-for-noobs--net-10488