What are the advantages and disadvantages of using mysqli versus PDO for database connections in PHP?

When choosing between mysqli and PDO for database connections in PHP, it's important to consider the advantages and disadvantages of each. mysqli is specifically designed for MySQL databases, which can make it easier to work with MySQL-specific features. It also has a procedural and object-oriented interface, giving developers flexibility in how they interact with the database. However, mysqli lacks support for other database systems, limiting its versatility. On the other hand, PDO is a database abstraction layer that supports multiple database systems, making it a more versatile choice for developers working with different databases. It also provides a consistent interface for interacting with databases, which can simplify code maintenance. However, PDO may have a slightly higher learning curve for developers who are not familiar with its syntax. Overall, the choice between mysqli and PDO will depend on the specific requirements of your project and your familiarity with each library.

// Using mysqli for database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
```

```php
// Using PDO for database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully"; 
} catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}