php code of troubling getting multiple value - php

Question

I have codes that should be getting value from mysql database, I can get only one value but I have while loop so it can get value and output data separated with comma. But I only get one value and cannot get multiple value. the result should be like this, // End main PHP block. Data looks like this: [ [123456789, 20.9],[1234654321, 22.1] ] here is the code:
<?php
// connect to MySQL
mysql_connect('localhost','','') or die("Can't connect that way!");
#mysql_select_db('temperature1') or die("Unable to select a database called 'temperature'");
if(ISSET($_GET['t']) && (is_numeric($_GET['t'])) ){
// message from the Arduino
$temp = $_GET['t'];
$qry = "INSERT INTO tempArray(timing,temp) VALUES(".time().",'$temp')";
echo $qry;
mysql_query($qry);
mysql_close();
exit('200');
}
// no temp reading has been passed, lets show the chart.
$daysec = 60*60*24; //86,400
$daynow = time();
if(!$_GET['d'] || !is_numeric($_GET['d'])){
$dayoffset = 1;
} else {
$dayoffset = $_GET['d'];
}
$dlimit = $daynow-($daysec*$dayoffset);
$qryd = "SELECT id, timing, temp FROM tempArray WHERE timing>='$dlimit' ORDER BY id ASC LIMIT 1008";
// 1008 is a weeks worth of data,
// assuming 10 min intervals
$r = mysql_query($qryd);
$count = mysql_num_rows($r);
$i=0;
$r = mysql_query($qryd);
$count = mysql_num_rows($r);
while($row=mysql_fetch_array($r, MYSQL_ASSOC)) {
$tid=$row['id'];
$dt = ($row['timing']+36000)*1000;
$te = $row['temp'];
if($te>$maxtemp) $maxtemp=$te; // so the graph doesnt run along the top
if($te<$mintemp) $mintemp=$te; // or bottom of the axis
$return="[$dt, $te]";
echo $return; //here I get all values [1385435831000, 21][1385435862000, 23][1385435892000, 22][1385435923000, 25][1385435923000, 22]
$i++;
if($i<$count) $return= ","; echo $return; // if there is more data, add a ',' however, it return me ,,,[1385435923000, 22]
$latest = "$dt|$te"; // this will get filled up with each one
}
mysql_close();
// convert $latest to actual date - easier to do it here than in javascript (which I loathe)
$latest = explode('|',$latest);
$latest[0] = date('g:ia, j.m.Y',(($latest[0])/1000)-36000);
?>

Answer 1

You're just assigning $return to the values from the last row your while loop grabbed instead of concatenating it. Try this
$return = "[";
while($row=mysql_fetch_array($r, MYSQL_ASSOC)) {
$tid=$row['id'];
$dt = ($row['timing']+36000)*1000;
$te = $row['temp'];
if($te>$maxtemp) $maxtemp=$te; // so the graph doesnt run along the top
if($te<$mintemp) $mintemp=$te; // or bottom of the axis
$return.="[$dt, $te]";
$i++;
if($i<$count) $return .= ", ";// if there is more data, add a ','
$latest = "$dt|$te"; // this will get filled up with each one
}
$return .= "]";