How to connect to a database

Short answer

Create a PDO object. For MySQL the connection string looks like this: mysql:host=localhost;dbname=shop;charset=utf8mb4, followed by the user name and the password. The example uses in-memory SQLite so that it runs without a server:

<?php
 
$pdo = new PDO('sqlite::memory:', null, null, [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
]);
 
echo $pdo->query('SELECT 1 + 1')->fetchColumn();

Output:

2

A connection error

If the database is unavailable, PDO throws an exception. Show the visitor a general message and write the details to the log:

<?php
 
try {
    new PDO('sqlite:/no/such/folder/app.db');
    echo 'connected';
} catch (PDOException $error) {
    echo 'Database is unavailable';
}

Output:

Database is unavailable