This page explanation:
You can save the edited information.
※Click the Update button to receive an alert.
※Click “OK” on the alert to update data.

This page function:
Save(edited information)

① Controller

Controller:/app/controller/customerController.php

<?php
class customer{
   //~~~
   public function action_update($targetId){ //updated function

      //Get POST data
      $first_name = isset($_POST['first_name']) ?? $_POST['first_name'] : '';
      $last_name = isset($_POST['last_name']) ?? $_POST['last_name'] : '';
      $birthday = isset($_POST['birthday']) ?? $_POST['birthday'] : '';
      $gender = isset($_POST['gender']) ?? $_POST['gender'] : '';
      $blood = isset($_POST['blood']) ?? $_POST['blood'] : '';
      $comment = isset($_POST['comment']) ?? $_POST['comment'] : '';

      //Retrieve one data from the database
      $custmanageObj = ORM::for_table(customer)->where('id', (int)$targetId)->find_one();
      $custmanageObj->first_name = $first_name;
      $custmanageObj->last_name = $last_name;
      $custmanageObj->birthday = $birthday;
      $custmanageObj->gender = $gender;
      $custmanageObj->blood = $blood;
      $custmanageObj->comment= $comment;
      //save do
      $custmanageObj->save();

      //~~~
      redirectUrl('customer'); //class “customer” to redirect.
   }
   //~~~
}
?>

② View

View:/app/view/customer_edit.php

<!--~~~-->
    <form method='post' action=''<?= SYSTEM_DIR . '/customer/update/'.$targetId; ?>''>
        <!--↑The "action=..." specifies the URL to which data is sent when the submit button is pressed.-->
        <button type="button" class="btn btn-success " id="update-btn">更新</button>
        <button type="button" class="btn btn-danger" id="delete-btn" >削除</button>
        <table>
            <!--~~~-->
            <input type='text' name='last_name' value='<?php echo $last_name; ?>'>
            <input type='text' name='first_name' value='<?php echo $first_name; ?>'>
            <input type='text' name='birthday' value='<?php echo $birthday; ?>'>
            <input type='text' name='gender' value='<?php echo $gender; ?>'>
            <input type='text' name='blood' value='<?php echo $blood; ?>'>
            <input type='text' name='comment' value='<?php echo $comment; ?>'>
            <!--~~~-->
        </table>
    </form>
<!--~~~-->