What are some common mistakes to avoid when writing PHP code for database queries?

One common mistake to avoid when writing PHP code for database queries is not properly sanitizing user input, which can lead to SQL injection attacks. To prevent this, always use prepared statements and parameterized queries to securely interact with the database. 

// Incorrect way without prepared statements
$user_input = $_POST['username'];
$query = "SELECT * FROM users WHERE username = '$user_input'";
$result = mysqli_query($connection, $query);

// Correct way with prepared statements
$user_input = $_POST['username'];
$query = "SELECT * FROM users WHERE username = ?";
$stmt = mysqli_prepare($connection, $query);
mysqli_stmt_bind_param($stmt, "s", $user_input);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

Keywords

SQL injection prepared statements PDO mysqli error handling

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