Simple formatting of multidimensional array from mysql in php

Question

Hello.
I have an array of results from mysql relational tables. It looks similar to this:

array(10) {
  [0]=>
  object(stdClass)#14 (35) {
    ["eventID"]=>
    string(1) "1"
    ["eventTitle"]=>
    string(7) "EVENT 1"
    ["artistID"]=>
    string(1) "1"
    ["artistName"]=>
    string(8) "ARTIST 1"
    ["artistDescription"]=>
    string(20) "ARTIST 1 description"
    // etc.
  }
  [1]=>
  object(stdClass)#15 (35) {
    ["eventID"]=>
    string(1) "1"
    ["eventTitle"]=>
    string(7) "EVENT 1"
    ["artistID"]=>
    string(1) "2"
    ["artistName"]=>
    string(8) "ARTIST 2"
    ["artistDescription"]=>
    string(20) "ARTIST 2 description"
    // etc.
  }
  [2]=>
  object(stdClass)#16 (35) {
    ["eventID"]=>
    string(1) "1"
    ["eventTitle"]=>
    string(7) "EVENT 1"
    ["artistID"]=>
    string(1) "3"
    ["artistName"]=>
    string(8) "ARTIST 3"
    ["artistDescription"]=>
    string(20) "ARTIST 3 description"
    // etc.
  }
  [3]=>
  object(stdClass)#17 (35) {
    ["eventID"]=>
    string(1) "2"
    ["eventTitle"]=>
    string(7) "EVENT 2"
    ["artistID"]=>
    string(1) "5"
    ["artistName"]=>
    string(8) "ARTIST 5"
    ["artistDescription"]=>
    string(20) "ARTIST 5 description"
    // etc.
  }
  [4]=>
  object(stdClass)#17 (35) {
    ["eventID"]=>
    string(1) "2"
    ["eventTitle"]=>
    string(7) "EVENT 2"
    ["artistID"]=>
    string(1) "7"
    ["artistName"]=>
    string(8) "ARTIST 7"
    ["artistDescription"]=>
    string(20) "ARTIST 7 description"
    // etc.
  }
//etc.
}

I want to make a multidimensional array which would look like this one:

array(2) {
  [1]=>
  array(9) {
    ["eventID"]=>
    string(1) "1"
    ["eventTitle"]=>
    string(7) "EVENT 1"
    ["artists"]=>
    array(3) {
      [1]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 1"
        ["artistDescription"]=>
        string(20) "ARTIST 1 description"
      }
      [2]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 2"
        ["artistDescription"]=>
        string(20) "ARTIST 2 description"
      }
      [2]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 3"
        ["artistDescription"]=>
        string(20) "ARTIST 3 description"
      }
    }
  }
  [2]=>
  array(9) {
    ["eventID"]=>
    string(1) "2"
    ["eventTitle"]=>
    string(7) "EVENT 2"
    ["artists"]=>
    array(3) {
      [1]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 5"
        ["artistDescription"]=>
        string(20) "ARTIST 5 description"
      }
      [2]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 2"
        ["artistDescription"]=>
        string(20) "ARTIST 7 description"
      }
      [2]=>
      array(2) {
        ["artistName"]=>
        string(8) "ARTIST 3"
        ["artistDescription"]=>
        string(20) "ARTIST 7 description"
      }
    }
  }
}

I started to create an array in a FOR loop but I was stuck with creating this artists[] array and I'm totally confused last 30 mins =)

Thank you in advance for any help!

Answer 1

<?php
$output = array();
foreach($resultset as $event)
{

   $eventId = $event['eventID'];
   $artistId = $event['artistID'];
   //Using the eventId as the index ensures the event is unique and easy to lookup in the array.
   $output[$eventId]['eventTitle'] = $event['eventTitle'];
   $output[$eventId]['eventID'] = $event['eventID'];
   //Using the 'artistID' as the index of artists ensures each artist is unique and easy to lookup.
   $output[$eventId]['artists'][$artistId]['artistID'] = $artistId;
   $output[$eventId]['artists'][$artistId]['artistName'] = $event['artistName'];
   $output[$eventId]]['artists'][$artistId]['artistDescription'] = $event['artistDescription'];
}
echo '<pre>' . print_r($output,true) . '</pre>';