Using Jquery to update a page when a database is modified

Question

I want to update a page when my database is modified. I want to use jquery for doing this. Question not clear? Then have a look at this, Suppose this is my page:

<?php
 $query=mysql_query("select * from tbl1 where user='admin'");
 if(mysql_num_rows?($query)!=0)
 {
   echo 'Table 1 has values';
 } else {
   echo 'Table1 is empty';


}
?>

This action should be performed whenever any new entry is added to the database. Now suppose I add an entry to the database manually then the page should automatically show the result as "Table1 has values". I know it can be used by using refresh page periodically but I don't want to use it. Instead I want to try something other, like ajax polling? Can someone give me a demo?

Answer 1

You can use long polling, but do a lot of research first. Your server may kill the request that appears to be open for a long amount of time.

In PHP, your code will look something like...

set_time_limit(0);

while (TRUE) {
   // Query database here
   if ($results) {
      echo json_encode($results);
      exit;
   }

   sleep(1);
}

Answer 2

You can use Ajax jQuery Framework with Ajax:

http://www.w3schools.com/Ajax/default.asp
http://api.jquery.com/jQuery.ajax/

It will call the server side script Asynchronously and update your page accordingly. You can use jQuery to specify the format of the update also.