PHP while循环从mysql数据库获取值，如果它等于$ i值

I'm trying to get a value to be inserted into a table on a webpage if the value equals $i.

$i starts at a number and decreases every loop. i can get it to work but it outputs multiple lines for each $i equivalent to the results in the table

I've reworked the code using everyones feedback to get this.

Echo "<tr><th colspan='3'><center>$rackname</th> </tr>" ;
    for ($i=$RUtotal; $i > 0; $i--)
        { 
            echo" <tr class='rackbg'><td class='i'><center>$i</td>" ;
            $sql1 = "SELECT racks.rackID, racks.rackname, devices.deviceID, devices.deviceName, racks.rackRU, devices.deviceRU, devices.RUcount
                    FROM racks LEFT JOIN devices ON racks.rackID = devices.rackID
                    WHERE devices.rackID = '$rackID'";
            $query1 = mysql_query($sql1);

            while ($row = mysql_fetch_assoc($query1))
                {

                    $deviceru = $row['deviceRU'];
                    $deviceID = $row['deviceID'];
                    $device = $row['deviceName'];
                    $deviceRUC = $row['RUcount'];

                    if ($deviceru == $i) 
                        { 
                            echo '<td class="device" rowspan='.$deviceRUC.'><a onclick=window.location="/devices.php?id='.$deviceID.'">'.$device.'</a></td><td rowspan='.$deviceRUC.'></td></tr>';
                        }
                    else
                        {
                            ;
                        }

                } 
        }

    Echo "<tr class='rackb'><th colspan='3'>a</th></tr> " ;

This works to a degree (picture1) but when i add echo "" to the else statement it displays all wrong. (picture 2)

Any help would be greatly appreciated

Picture1 - http://imageshack.us/photo/my-images/263/examplewq.png/

Picture2 - http://imageshack.us/photo/my-images/269/example2jp.png/

This is looping $i times, within the outer while loop. This means you are getting the table repeated over and over again.

I suggest you remove the outer while loop.

I can't quite see what you're trying to do but what it looks like to me is that you want all the items from racks joined with their relevant device and displayed in order of deviceRU. Does this help:

echo "<tr><th colspan='3'><center><b>$rackname</th></tr>" ;

$sql1 = "SELECT racks.rackID, racks.rackname, devices.deviceID, devices.deviceName, racks.rackRU, devices.deviceRU, devices.RUcount
   FROM racks LEFT JOIN devices ON racks.rackID = devices.rackID
   WHERE racks.rackID = '$rackID' AND devices.deviceRU <= ".intval($RUtotal)."
   ORDER BY devices.deviceRU;"
$query1 = mysql_query($sql1);
while ($row = mysql_fetch_array($query1))
    {
    $deviceru = $row['deviceRU'];
    $deviceID = $row['deviceID'];
    $device = $row['deviceName'];
    $deviceRUC = $row['RUcount'];

    echo'<tr class="rackbg"><td class="i">'.$i.'</td><td class="device"><a href="/devices.php?id='.$deviceID.'">'.$device.'</a></td><td></td></tr>';
}

I've used a LEFT (inner) JOIN in the SQL instead of the outer join that was there before as it'll return less results and might solve your problem. I've ordered the results by deviceRU and only returned results which have deviceRU less than or equal to $RUtotal (as I think the example was showing).

I've also removed the tags, these should be replaced by using CSS to centre either all td elements or centering class="device" and class="i" e.g.:

.device, .i {
     text-align: center;
 }

I've also swapped your abc to abc which is the correct format for a link.

Could you describe more of the context as it's difficult to see your intention from your post.

Mat

As Peetz said, you don't need nested loop. You need something like:

$i = $RUtotal;
// ...
while ($row = mysql_fetch_array($query1)) {
    // ...
    if ($deviceru == $i) {
        // ...
    } else {
        // ...
    }
    // ...
    $i--;
}