What are some common mistakes to avoid when working with PHP and MySQL databases?

One common mistake to avoid when working with PHP and MySQL databases is not sanitizing user input before inserting it into the database. This can leave your application vulnerable to SQL injection attacks. To prevent this, always use prepared statements with parameterized queries to securely interact with the database. 

// Incorrect way (vulnerable to SQL injection)
$username = $_POST['username'];
$password = $_POST['password'];

$sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";
$result = mysqli_query($conn, $sql);

// Correct way (using prepared statements)
$stmt = $conn->prepare("INSERT INTO users (username, password) VALUES (?, ?)");
$stmt->bind_param("ss", $username, $password);

$username = $_POST['username'];
$password = $_POST['password'];

$stmt->execute();
$stmt->close();

Keywords

SQL injection PDO prepared statements error handling data validation

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