timed loop

[josheee12]

i am writing a website that has a chat board for 1:1 online tutoring.  i did not write the chat app, and do not have access to it's database.  what i need to figure out is how to redirect the user once the tutor logs off.  currently, when a tutor logs in, it sets a value in a mysql database seperate to the chat one.  i want to find a way to query the db every 2 minutes, and if the admin is not logged on, redirect the user.  how can i use sleep in an while loop?

[oni-kun]

This code is rough but should work..

$result = @mysql_query("SELECT * FROM whatever");
while ($record=mysql_fetch_array($result)) {
echo $record["adminonline"];
flush(); //Prevent output buffer from sleeping
sleep(60*2); //Two minutes
}

You'd need to rewrite the while loop a bit to suit it to your own needs to finding if the admin/tutor is online, but sleep() will stop it from running the script continuously, flush() will prevent the script from sleeping, and make it just the while loop.

[ignace]

$result = @mysql_query("SELECT * FROM whatever");
while ($record=mysql_fetch_array($result)) {
echo $record["adminonline"];
sleep(60*2); //Two minutes
flush(); //Prevent output buffer from sleeping
}

 

First of all, why  use the @ (error-suppressing operator)?

$result = @mysql_query("SELECT * FROM whatever");

 

mysql_query() only returns a resource or true or false, so no need to suppress.

 

The code also need a slight modification or will throw a nasty error otherwise when your query fails and you try to access it with mysql_fetch_array() as it expects a resource and gets a boolean (false).

 

Also don't use mysql_fetch_array() if you only use the the associative part, use mysql_fetch_assoc() instead.

 

mysql_fetch_array() returns the result both as a numerical and as a associative array (unless a second parameter MYSQL_NUM or MYSQL_ASSOC is provided by default MYSQL_BOTH) thus doubling the result (numerical and associative instead of only the associative part) + your memory is affected to, the cached mysql result set + your array that contains the result in both a numerical and an associative array.

 

$result = mysql_query("SELECT * FROM whatever");
if ($result && mysql_num_rows($result)) {
    while ($record=mysql_fetch_assoc($result)) {
        echo $record["adminonline"];
        sleep(60*2); //Two minutes
        flush(); //Prevent output buffer from sleeping
    }
}//Else: Query failed

[josheee12]

<?php

$link = mysql_connect('localhost', '*****', '*****');
if (!$link) {
    die('Error connecting to the DB.');
}

$db_selected = mysql_select_db('*****', $link);
if (!$db_selected) {
    die ('Error connecting to the DB.');
}
$result = mysql_query("SELECT * FROM *****");


if ($result && mysql_num_rows($result)) {
    while ($record=mysql_fetch_array($result)) {
        echo $record["is_loggedin"];
        sleep(5); //5 secs for testing purposes
        flush(); //Prevent output buffer from sleeping
    }
}//Else: Query failed
mysql_close($link);
?>

 

is_loggedin is a boolean in mysql.  the page waits 5 secs for localhost, then shows whatever is in the db.  i go back to the mysql query browser, and the page does not change.