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phpmultidimensional-array
Steve
Steve

Reputation: 401

PHP Trouble with multidimensional Arrays

I am currently attempting to extract data from a mysql DB and then place it into a multidimensional array, using the device name as a key.

The issue I'm having is that every time I iterate through the results the code im using kills the last item and replaces it.

Here is the code;

##sql connection##
$result = mysql_query(SELECT Device.DeviceID, Device.DeviceName, History.HistoryRec, History.HistoryDetectedDate from Device JOIN History ON Device.DeviceID=History.DeviceID WHERE History.Active_LastRound = 1 AND History.DetectedDate <= $hrs);
if (!$result){
die('invaild query:' . mysql_error());

while($row = mysql_fetch_array($result))
{
$last24hoursarray[$row['DeviceName']] = array($row['HistoryRec']);
}

So the issue i have is that my results set has multiple records with the same device name, and i cant work out how to put them into an array so that they do not overwrite the last item

for example i want

switch1 => issue1
switch1 => issue2
switch1 => issue3
switch2 => issue1
etc

but what i get is;

switch1 => issue3
switch2 => issue1

Thanks in advance. This is the first bit of PHP i have written, so please be gentle :D

Upvotes: 1

Views: 101

Answers (5)

codegen
codegen

Reputation: 21

First of all, arrays only allow a single value for keys. You will not be able to get.

switch1 => issue1
switch1 => issue2
switch1 => issue3

You can get 

switch1 => [issue1, issue2, issue3]

I haven't taken the time to test the code, but it would be something like:

while($row = mysql_fetch_array($result)){
  if (array_key_exists ( $row['DeviceName'] , $last24hoursarray ){
    // append to existing issue.
    $last24hoursarray[$row['DeviceName']][] = array($row['HistoryRec']);
  } else{
    //No device name, create the array with issue.
    $last24hoursarray[$row['DeviceName']] = array($row['HistoryRec']);
  }
}

Upvotes: 2

Ed Manet
Ed Manet

Reputation: 3178

It doesn't look like you're using a multi-dimensional array here. A multi-dimensional array is more like this:

switch1 = array(issue1, issue2, issue3);
switch2 = array(issue1);
multi = array(switch1, switch2);

issue = multi[0][1];  // issue2

Upvotes: 0

Andrew
Andrew

Reputation: 2164

The reason that this code is not working is that PHP associative arrays only store one value per key of the array. This is so that you can lookup a unique value by key, which is the entire purpose of associative arrays. The code from Merca's example should work great, as it will create an array of values for each key in your associative array.

Upvotes: 0

Sebastian Breit
Sebastian Breit

Reputation: 6159

try creating a new array for each device:

$last24hoursarray[$row['DeviceName']] = new array($row['HistoryRec']);

Upvotes: 0

Miroslav
Miroslav

Reputation: 1960

PHP Array keys are unique, so you would not be able to store multiple values under the same key, try the following:

while($row = mysql_fetch_array($result)) {
        $last24hoursarray[$row['DeviceName']][] = $row['HistoryRec'];
}

Upvotes: 5

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