Are there best practices for structuring PHP functions to avoid issues like missing database entries?

When working with PHP functions that interact with a database, it's important to handle potential issues like missing database entries to prevent errors in your application. One best practice is to check if the database query returned any results before trying to access them in your code. This can be done by checking the number of rows returned by the query and handling the case where no rows are found gracefully.

// Example of checking for missing database entries in a PHP function
function get_user_data($user_id) {
    $query = "SELECT * FROM users WHERE id = $user_id";
    $result = mysqli_query($connection, $query);

    if(mysqli_num_rows($result) > 0) {
        // Process the user data
        $user_data = mysqli_fetch_assoc($result);
        return $user_data;
    } else {
        // Handle the case where no user data is found
        return null;
    }
}