What are some common errors or pitfalls to watch out for when querying data from a database in PHP?

One common error when querying data from a database in PHP is not properly sanitizing user input, which can lead to SQL injection attacks. To prevent this, always use prepared statements with parameterized queries when querying the database. 

// Connect to the database
$pdo = new PDO('mysql:host=localhost;dbname=mydatabase', 'username', 'password');

// Prepare a SQL statement with a placeholder for user input
$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');

// Bind the user input to the placeholder
$stmt->bindParam(':username', $_POST['username']);

// Execute the query
$stmt->execute();

// Fetch the results
$results = $stmt->fetchAll();

Keywords

SQL injection PDO prepared statements error handling database connection

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