Polling a Database for changes

[Craig Hopson]

ok there is probably a simple way to do this but i cant find it...I would like to auto update from mysql but only new entrys here is what i have index.php

<script type="text/javascript" src="js/jquery-1.7.2.min.js"></script><script type="text/javascript">$(function() {	 setInterval(function() {	    $("<div/>").hide().load("inc/feedx.php", function() {	    $(this).prependTo("#foo").slideDown("slow");	    });	 }, 5000);});</script><div id="foo"></div>$result = mysql_query("SELECT e.*,f.* FROM emails as e left join files as f on f.email_id=e.id WHERE e.subject='1' ORDER BY e.date DESC LIMIT 20");while($row = mysql_fetch_array($result)){//somestuff}

feedx.php

$result = mysql_query("SELECT e.*,f.* FROM emails as e left join files as f on f.email_id=e.id WHERE e.subject='1' ORDER BY e.date DESC LIMIT 1");while($row = mysql_fetch_array($result)){//somestuff}

the code above works BUT it keeps adding the last SQL entry and "not just new ones"

[justsomeguy]

The PHP code should also return a timestamp that gives the time of the last time data was requested. The Javascript code should send that timestamp back to PHP, and PHP can use it to determine the last time data was loaded and find the data that has been added since then. All of the rows in the database will need timestamps so that you know which ones are the new ones.

[Craig Hopson]

the timestamp is there but how do i do that (Javascript) i can figure out the php

[justsomeguy]

You get the current timestamp with the time function. PHP sends that to Javascript along with the rest of the data. Javascript saves the timestamp that it got from PHP. The next time it sends a request to PHP, it sends the timestamp also. PHP gets the timestamp and uses that as the last time that Javascript got data, and PHP returns everything since then. You don't want Javascript to generate the timestamp, it should just save the one it got from PHP and send it back.

[Craig Hopson]

i understand that how do i get javascript to receive the timestame

[justsomeguy]

It's part of the response that PHP sends back. I usually have my PHP respond with a JSON string when it's responding to ajax. You'll have to change the jQuery code, of course.

[justsomeguy]

Another option would be the session, you can store the timestamp of the last request there and leave Javascript out of it.

[Craig Hopson]

that's the problem i don't understand javascript AT ALL i dont know why i read the tutorial like 3 times

[Craig Hopson]

Another option would be the session, you can store the timestamp of the last request there and leave Javascript out of it.

oh yes i can do that thanks bud

[thescientist]

it's gonna take a little more time than just reading it. I would recommend practicing some of the code in the references as well, so you can get an understanding for how the code works. practice with functions, variables, etc. part of AJAX requires understanding the concept of callbacks as well. it's a little tricky, but is arguablly one of JS's most useful features.

[Craig Hopson]

ok i got it working using SESSION just fine but it twitches i think its the javascript when there is no update it starts to move then stops "twitching"lol

<script type="text/javascript">$(function() {	 setInterval(function() {	    $("<div/>").hide().load("inc/feedx.php", function() {	    $(this).prependTo("#foo").slideDown("slow");	    });	 }, 5000);});</script>

[justsomeguy]

You're always adding something to the document regardless of whether PHP returned anything.