Explanation:In PHP, the GET and POST methods are used to retrieve and send data between the client (typically a web browser) and the server. These methods are commonly used in web forms to submit user input or to pass data to a PHP script for processing. Here's an overview of the GET and POST methods in PHP:GET Method:1. The GET method appends data to the URL as query parameters.2. The data is visible in the URL, making it less secure for sensitive information.3. The data is limited in size due to URL length restrictions.4. The data can be accessed in PHP using the $_GET superglobal variable.5. Example usage: ``.POST Method:1. The POST method sends data in the HTTP request body without exposing it in the URL.2. The data is more secure compared to the GET method as it is not directly visible.3. The data can be of larger size compared to the GET method.4. The data can be accessed in PHP using the $_POST superglobal variable.5. Example usage: ``.To retrieve data submitted using either method, you can access the data through the corresponding superglobal variables in PHP. For example:```phpif ($_SERVER["REQUEST_METHOD"] == "GET") { // Retrieve GET data $data = $_GET["data"]; // Process the data // ...} elseif ($_SERVER["REQUEST_METHOD"] == "POST") { // Retrieve POST data $data = $_POST["data"]; // Process the data // ...}```Remember to sanitize and validate the data received from user inputs to ensure security and reliability in your PHP application.

This is a pretty common type of thing for a PHP application to do. The general pattern is:

1. Pull a list of items from a database and display them with links to interact with specific items.
2. When a link is clicked, display a form with the information of the selected item.
3. When the form is submitted, save the user input to the selected item.

The minimum you need to implement this pattern is the following:

Step 1 (display the items):

<?php
// using mysqli for example here, but the same general idea for pdo or any other
$result = mysqli_query('SELECT id, some_text, other_columns FROM your_table WHERE criteria');
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
    $id = htmlspecialchars($row['id']);
    $text = htmlspecialchars($row['some_text']);
    echo '<a href="url/to/your_form.php?id=' . $id . '">' . $text . '</a><br>';
}
?>

Clicking a link (<a>) sends an HTTP GET request to the URL in its href parameter.

Step 2 (display the form):

When PHP handles the request, anything you have included in the query string of the URL (the ?id=x portion) will be availabe in the $_GET array. There are two ways you can handle this piece of data so that it can be passed on to step 3. One way is to include it in the URL in the action parameter of your form:

<form action="url/to/submission_handler.php?id=<?php echo $_GET['id']; ?>" method="post">

Another way is to include a hidden form element that contains the ID.

<form action="url/to/submission_handler.php" method="post">
    <input type="hidden" name="id" value="<?php echo $_GET['id']; ?>">

Step 3 (handle the form submission):

In this step, if you have passed the ID via the action parameter, it will be available in the $_GET array ($_GET['id']), and if you have passed it via an input on the form, it will be available in the $_POST array. ($_POST['id']). Either way, you should be able to access it for use in your query.

<?php
$id = $_GET['id']; // or $_POST['id'], depending on which way you handled it on your form

// Using a prepared statement here for example rather than concatenating values into the 
// SQL string, in order to reduce risk of SQL injection

// (Assuming $mysli is a connected mysqli object)
$stmt = $mysqli->prepare('UPDATE your_table SET ... WHERE id=?');
$stmt->bind_param("i", $id);
$stmt->execute();
?>

Either method of passing the id from your form to the script that handles its submission is perfectly valid, functional and commonly used. As far as I know, which way you should do it is really just determined by your own personal preference. But you should note that passing parameters in the query string of the action paramater will only work for forms with method="post". If you ever need to use method="get" instead, only the values in the form fields will be available in $_GET; parameters in the query string will be ignored. (For forms that will make changes on your server, (INSERT, UPDATE, or DELETE queries, writing to files, etc.) you should always be using method="post" anyway, but just FYI.)