Value not saving in array - php

Question

I have an array which have this structure:
$queues[n] Array (
[id] => integer
[idClient] => integer
[name] => string
[people] => integer )
Which is populated with:
$query = "SELECT clients.idClient AS 'idClient', queues.idQueue AS 'idQueue', queues.name AS 'name' FROM clients, queues WHERE clients.idClient = queues.client";
$queues = null;
$result = mysql_query($query);
if ($result){
while ($queue = mysql_fetch_assoc($result)){
$queues[] = array ("idClient" => $queue['idClient'], "id" => $queue['idQueue'], "name" => $queue['name'], "people" => 0);
}
}
Each 'n' value match a queue from Database and people, by default is set to 0.
After populating the array I query the database again with each queue to other table to obtain the number of people in queue with a query like this:
SELECT COUNT(*) FROM peoplequeued WHERE queue ='".$queue['name']."'
And then:
$result = mysql_query($query);
if ($result){
$num_people = mysql_fetch_row($result);
$queue['people'] = $num_people[0];
}
And something strange happens here. If I echo the $queue['people'] in the foreach, it shows fine the value it got but if I preview the full array before returning it, it's back to 0.
What could be happening?

Answer 1

My guess is that you're looping through $queues with foreach loop like this:
foreach ( $queues as $queue ) {
$result = mysql_query($query);
if ($result){
$num_people = mysql_fetch_row($result);
$queue['people'] = $num_people[0];
}
}
If so, there's no "link" between $queue and $queues[$n], i.e., by modifying $queue, you do NOT modify $queues.
If this is the case, you should either use $queue as reference variable, or modify $queues[$n] with $n being an index.
foreach ( $queues as &$queue ) { // add & so $queue is a reference to an element in $queues
$result = mysql_query($query);
if ($result){
$num_people = mysql_fetch_row($result);
$queue['people'] = $num_people[0];
}
}
unset($queue); // drop the reference, otherwise you might have unexpected results after modifying $queue outside the loop
... or ...
foreach ( $queues as $n => $queue ) { // store index of "current" element in $n
$result = mysql_query($query);
if ($result){
$num_people = mysql_fetch_row($result);
$queues[$n]['people'] = $num_people[0]; // change $queue to $queues[$n]
}
}
Alternatively, I would advise you to think about getting all data in a single statement. It looks like something like this might work for you:
select
baseTable.id,
baseTable.idClient,
baseTable.name,
peopleCount.count as people
from
baseTable
left join (
select
count(*) as count,
queue
from
peoplequeued
group by
queue
) as peopleCount on peopleCount.queue = baseTable.name

Answer 2

It sounds like you're probably using a foreach loop to cycle through your $queues array, like this:
foreach($queues as $queue) {
}
Each $queue variable generated is a copy, and changes to it aren't saved to the $queues variable. To save changes as you're intending, you need to do something like:
foreach($queues as $k => $queue) {
$queue['people'] = 10;
$queues[$k] = $queue;
// or, more efficiently...
$queues[$k]['people'] = 10;
}
In PHP5 you can also reference. See http://uk.php.net/manual/en/control-structures.foreach.php