too long

How do I notify user on dashboard(index.php) as soon as new records get created in database or any changes made in database

Iknow I need to query like

CREATE TRIGGER notifyMe

    ON table1
    AFTER INSERT, UPDATE, DELETE 
    AS
       EXEC msdb.dbo.sp_send_dbmail
            @profile_name = 'DB AutoMailer',
            @recipients = 'user@example.com',
            @body = 'The DB has changed',
            @subject = 'DB Change';
    GO

but dont know how to do it by using Yii2 Events

In controller:

  Yii::$app->session->setFlash('success', "Your message to display");

In view

<?php if (Yii::$app->session->hasFlash('success')): ?>
  <div class="alert alert-success alert-dismissable">
  <button aria-hidden="true" data-dismiss="alert" class="close" type="button">×</button>
  <h4><i class="icon fa fa-check"></i>Saved!</h4>
  <?= Yii::$app->session->getFlash('success') ?>
  </div>
<?php endif; ?>