title: create a service to check external database frequently
body: <p>I am new in android and i develop an application that receive data from MYSQL external database using PHP.</p>
  
  <p>I need to create a service to check frequently the database if there is any change made on it  the end user will get notification , so how i can create this like this service ?? 
  any article to read ?!</p>
  
  <p>thanks in advance</p>