What potential pitfalls should be considered when checking for existing usernames in a database using PHP?

When checking for existing usernames in a database using PHP, it's important to consider potential pitfalls such as SQL injection attacks. To mitigate this risk, always use prepared statements or parameterized queries to prevent malicious users from manipulating the SQL query. Additionally, ensure that the input data is properly sanitized to avoid any unexpected behavior. 

// Example of checking for existing username using prepared statements
$username = $_POST['username'];

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

if($stmt->rowCount() > 0){
    echo "Username already exists";
} else {
    echo "Username is available";
}

Keywords

SQL injection prepared statements PDO data validation error handling

Related Questions