What are some potential pitfalls to be aware of when handling relational data in PHP?

One potential pitfall when handling relational data in PHP is the risk of SQL injection attacks if user input is not properly sanitized. To prevent this, always use prepared statements or parameterized queries to interact with the database. 

// Example of using prepared statements to handle relational data in PHP
$pdo = new PDO('mysql:host=localhost;dbname=mydatabase', 'username', 'password');

$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');
$stmt->bindParam(':username', $username);
$stmt->execute();

while ($row = $stmt->fetch()) {
    // Process the data retrieved from the database
}

Keywords

SQL injection data validation foreign key constraints PDO normalization

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