What are the best practices for structuring PHP scripts to ensure that input validation, database updates, and output display are done in the correct order?

To ensure that input validation, database updates, and output display are done in the correct order, it is best practice to follow the MVC (Model-View-Controller) design pattern. This involves separating the concerns of data manipulation (Model), user interface (View), and application logic (Controller). By structuring your PHP scripts in this way, you can ensure that input validation is handled first in the Controller, followed by database updates in the Model, and finally output display in the View. 

```php
// Controller (input validation)
if($_SERVER["REQUEST_METHOD"] == "POST") {
    // Validate input
    $input = $_POST['input'];
    
    // Proceed to Model for database update
    require_once 'model.php';
    $updated = updateDatabase($input);
    
    // Proceed to View for output display
    require_once 'view.php';
    displayOutput($updated);
}
```
In this example, the Controller handles input validation, the Model updates the database, and the View displays the output. This separation of concerns ensures that each step is executed in the correct order.

Keywords

input validation database updates output display PHP scripts structuring

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