Question

So, basically I’m trying to make a datacenter cab diagram. We have an excel spreadsheet, but this is not easy to update, nor easily searchable. I have three tables in a MySQL DB; the db is: racks, the tables are: cabinets, devices, & datacenters – each row in each of the tables represents what it is. The cabinet table has a column that designates how tall it is in U (some cabinets in some datacenters are taller than others). So, when the php draws a cabinet, it draws the cabinet in the respective height. So far, everything works in regards to grouping the datacenters and their containing cabinets and their respective heights. My issue is that I can’t seem to populate more than one device per cabinet. This is the entire page, and the MySQL DB setup is below that:

<SCRIPT LANGUAGE="JavaScript" type="text/javascript">
<!--
    function clickHandler(e)
    {
        var targetId, srcElement, targetElement;
        if (window.event) e = window.event; 
        srcElement = e.srcElement? e.srcElement: e.target;
        if (srcElement.className == "Outline")
        {
                targetId = srcElement.id + "d";
                targetElement = document.getElementById(targetId);

            if (targetElement.style.display == "none")
                {
                        targetElement.style.display = "";
                        srcElement.src = "images/minus.gif";
                    } 
            else
                {
                    targetElement.style.display = "none";
                    srcElement.src = "images/plus.gif";
                }
        }
    }
    document.onclick = clickHandler;
-->
</SCRIPT>
<noscript>You need Javascript enabled for this page to work correctly</noscript>
<?
function sql_conn()
{
    $username="root";
    $password="root";
    $database="racks";
    $server="localhost";

    @mysql_connect($server,$username,$password) or die("<h2 align=\"center\" class=\"red\">[<img src=\"images/critical.gif\" border=\"0\">] Unable to connect to $server [<img src=\"images/critical.gif\" border=\"0\">]</h2>");
    @mysql_select_db($database) or die("<h2 align=\"center\" class=\"red\">[<img src=\"images/critical.gif\" border=\"0\">] Unable to select $database as a database [<img src=\"images/critical.gif\" border=\"0\">]</h2>");
}

sql_conn();
$sql_datacenters="SELECT * FROM `datacenters`";

$sql_devices="SELECT * FROM `devices`";
$result_datacenters=mysql_query($sql_datacenters);
$result_devices=mysql_query($sql_devices);
$j=0;
echo "<table border='1' style='float:left;'>";
while ($datacenters_sqlrow=mysql_fetch_array($result_datacenters))
{
    echo "<tr><td>";
    echo "<h2 class='black' align='left'>";
    echo "<IMG SRC='images/plus.gif' ID='Out" . $j . "' CLASS='Outline' STYLE='cursor:hand;cursor:pointer'>"; // fancy icon for expanding-collapsing section
    echo " " . $datacenters_sqlrow['rack'] . ": " . $datacenters_sqlrow['cagenum'] . "</h2>"; // datacenter name and cage number
    echo "<div id=\"Out" . $j . "d\" style=\"display:none\">"; // opening of div box for section that is to be expanded-collapsed
    echo "<h3>" . $datacenters_sqlrow['notes'] . "</h3>"; // datacenter notes
    $sql_cabinets="SELECT * FROM `cabinets` WHERE `datacenter` = '$datacenters_sqlrow[0]' ORDER BY `cabinetnumber` ASC";
    $result_cabinets=mysql_query($sql_cabinets);
    while ($cabinets_sqlrow=mysql_fetch_array($result_cabinets))
    {
        $sql_devices="SELECT * FROM `devices` WHERE `datacenter` = '$datacenters_sqlrow[0]' AND `cabinet` = '$cabinets_sqlrow[1]' ORDER BY `ustartlocation` ASC";
        $result_devices=mysql_query($sql_devices);
        $num_devices=mysql_numrows($result_devices);
        echo "<table border='1' style='float:left;'>"; // opening of table for all cabinets in datacenter
        echo "<tr><td colspan='2' align='middle'>" . $cabinets_sqlrow[1] . "</td></tr>"; // cabinet number, spans U column and device name column
        while($row = mysql_fetch_array($result_devices))
        {
            $server = $row['devicename'];
            $ustart = $row['ustartlocation'];
        }
        for ($i = 0; $i < $cabinets_sqlrow[2]; $i++) // iterates through number of U in cabinet     
        {   
            $u = $cabinets_sqlrow[2] - $i; // subtracts current $i value from number of U in cabinet since cabinets start their numbers from the bottom up
            echo "<tr>";
            echo "<td width='15px' align='right'>$u</td>"; // U number
            echo "<td width='150px' align='middle'>";
            if ($u == $ustart) // determines if there is a device starting at this U
            {echo $server;} // device name
            else
            {echo "empty";} // empty space in cabinet
            echo "</td>";
            echo "</tr>";
        }
        $server="";
        $ustart="";

        echo "</table>"; // closes table opened in row 65
    }
    echo "</td></tr>";
    echo "</div>"; // close for div box that needs expanding-collapsing by fancy java
    $j++; // iteration for the fancy java expand-collapse
}
echo "</table>";
mysql_close();
?>

Here is the MySQL setup:

-- phpMyAdmin SQL Dump
-- version 3.5.1
-- http://www.phpmyadmin.net
--
-- Host: localhost
-- Generation Time: Nov 02, 2012 at 02:13 AM
-- Server version: 5.5.25
-- PHP Version: 5.4.4

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";

--
-- Database: `racks`
--

-- --------------------------------------------------------

--
-- Table structure for table `cabinets`
--

CREATE TABLE `cabinets` (
  `id` tinyint(3) NOT NULL AUTO_INCREMENT,
  `cabinetnumber` varchar(25) NOT NULL,
  `numberofu` varchar(3) NOT NULL,
  `datacenter` tinyint(3) NOT NULL,
  KEY `id` (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;

--
-- Dumping data for table `cabinets`
--

INSERT INTO `cabinets` (`id`, `cabinetnumber`, `numberofu`, `datacenter`) VALUES
(1, '0101', '45', 2),
(2, '0102', '45', 2),
(3, '0101', '50', 1),
(4, '0102', '50', 1),
(5, '0103', '50', 1);

-- --------------------------------------------------------

--
-- Table structure for table `datacenters`
--

CREATE TABLE `datacenters` (
  `id` tinyint(3) NOT NULL AUTO_INCREMENT,
  `rack` varchar(20) NOT NULL,
  `cagenum` varchar(255) NOT NULL,
  `notes` longtext NOT NULL,
  KEY `id` (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ;

--
-- Dumping data for table `datacenters`
--

INSERT INTO `datacenters` (`id`, `rack`, `cagenum`, `notes`) VALUES
(1, 'CAGE1', '', ''),
(2, 'CAGE2', '', ''),
(3, 'CAGE3', '', ''),
(4, 'CAGE4', '', ''),
(5, 'CAGE5', '', ''),
(6, 'CAGE6', '', ''),
(7, 'CAGE7', '', '');

-- --------------------------------------------------------

--
-- Table structure for table `devices`
--

CREATE TABLE `devices` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `devicename` varchar(255) NOT NULL,
  `datacenter` varchar(255) NOT NULL,
  `cabinet` varchar(255) NOT NULL,
  `frontorrear` tinyint(3) NOT NULL,
  `ustartlocation` varchar(255) NOT NULL,
  `usize` varchar(255) NOT NULL,
  `spare1` varchar(255) NOT NULL,
  `spare2` varchar(255) NOT NULL,
  `spare3` varchar(255) NOT NULL,
  KEY `id` (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;

--
-- Dumping data for table `devices`
--

INSERT INTO `devices` (`id`, `devicename`, `datacenter`, `cabinet`, `frontorrear`, `ustartlocation`, `usize`, `spare1`, `spare2`, `spare3`) VALUES
(1, 'SERVER1', '1', '0101', 1, '33', '1', '', '', ''),
(2, 'SERVER2', '1', '0102', 1, '36', '1', '', '', ''),
(3, 'SERVER3', '1', '0101', 1, '40', '2', '', '', '');

Answer 1

To directly address the problem (I’ll get to more in a little bit), you are iterating through the full list of devices and then – after you’re done looping through them all – you attempt to display them. Because of this, you’re only displaying the final device that was touched.

Your current code, truncated, is:

while($row = mysql_fetch_array($result_devices)) {
    $server = $row['devicename'];
    $ustart = $row['ustartlocation'];
}
for ($i = 0; $i < $cabinets_sqlrow[2]; $i++) {
    $u = $cabinets_sqlrow[2] - $i;
    ...
    if ($u == $ustart) {
        echo $server;
    }
    ...
}

If I understand what you’re trying to do, you’ll need to store each device into a “devices” array and loop through it during each iteration of your for loop. Try something like:

$devices = array();
while($row = mysql_fetch_array($result_devices)) {
    $devices[] = array(
        'server' => $row['devicename'],
        'ustart' => $row['ustartlocation']
    );
}
for ($i = 0; $i < $cabinets_sqlrow[2]; $i++) {
    ...
    $output = 'empty';
    foreach ($devices as $device) {
        if ($u == $device['ustart']) {
            $output = $device['server'];
            break;
        }
    }
    echo $output;
    ...
}

A more elegant way to accomplish this same task can be done using the ustartlocation as the index of the array, but it will require that the ustartlocation is unique to an individual device/server:

$devices = array();
while($row = mysql_fetch_array($result_devices)) {
    $devices[$row['ustartlocation']] = $row['devicename'];
}
for ($i = 0; $i < $cabinets_sqlrow[2]; $i++) {
    ...
    echo (isset($devices[$u]) ? $devices[$u] : 'empty');
    ...
}

This method will drop the need to loop through the list of devices each time, but again – it requires that the ustartlocation is unique.

Side Notes (additional, non-answer-specific critiques)

1. At the beginning of your code you execute $sql_devices="SELECT * FROMdevices"; and $result_devices=mysql_query($sql_devices);, but never use this object. It can and should be removed as it’s one extra (fairly heavy) query.

2. In the second while-loop you have the line $num_devices=mysql_numrows($result_devices);. There is no PHP-function mysql_numrows(), I believe this is a typo for the mysql_num_rows() function (that, or you have a custom-written function to do the same thing. Also, the $num_devices variable is never used so this line could actually be removed entirely.

3. You’re using the old and becoming-deprecated mysql_ functions (check out the warning-message on the top of any of the doc-pages for these functions; here’s mysql_connect() for reference). I, as well as the community, recommend you to upgrade to the mysqli_ or PDO methods.

4. Your code is open to unsanitized-SQL errors, not specifically limited to SQL-injection as it doesn’t appear you’re taking input directly from user-input, but also not ruling this factor out. For instance, what would happen if a cabinet or datacenter value contained a single-quote? Since you’re using mysql_ methods, I suggest you wrap each with mysql_real_escape_string() prior to using them in the database calls: $sql_cabinets="SELECT * FROM cabinets WHERE datacenter = '" . mysql_real_escape_string($datacenters_sqlrow[0]) . "' ORDER BY cabinetnumber";