How to edit key/value pairs in multidimensional, associative arrays? - php

Question

I hope my title makes sense, I'm no quite sure how to describe my problem in a shot way, so here is the long version:
I'm working in PHP and I have 2 MySQL tables that are displaying items and their specs (I cannot change the table structure).
T1 (Items)
+---------+--------+
| itemID | item |
+---------+--------+
| 1 | TV |
| 2 | Radio |
| 3 | Camera |
| ... | ... |
+---------+--------+
T2 (Specs)
+---------+--------+------+
| itemID | specID | spec |
+---------+--------+------+
| 1 | color | red |
| 1 | weight | 10 |
| 1 | price | 499 |
| 2 | color | blue |
| ... | ... | ... |
+---------+--------+------+
I want a multidimensional, associative array like this
array(
[0]=> array(
"itemID"=>"1",
"item"=>"TV",
"color"=>"red",
"weight"=>"10",
"price"=>"499")
[1]=> array(
"itemID"=>"2",
"item"=>"Radio",
"color"=>"blue",
...)
)
It seems impossible to me to achieve that with only one query.
I try to query the two tables separately, rearrange the key=>value in T2 and use array_merge.
What I have so far is the array from T1
array(
[0]=> array(
"itemID"=> "1",
"item"=>"TV")
[1]=> array(
"itemID"=> "2",
"item"=>"Radio")
[2]=> array(
"itemID"=> "3",
"item"=>"Camera")
...)
From T2 the array comes in the same form
array(
[0]=> array(
"itemID"=> "1",
"specID"=> "color",
"spec"=>"red")
[1]=> array(
"itemID"=> "1",
"specID"=> "weight",
"spec"=>"10")
[2]=> array(
"itemID"=> "1",
"specID"=> "price",
"spec"=>"499")
...)
After changing the array I will get a single numeric array, not two associative arrays like I want
array(
[0]=> array(
[0] => ["itemID" => "1","color" => "red","weight" => "10", "price" => "499"])
[1]=> array(
[0] => ["itemID" => "2","color" => "blue",...])
...)
My code is
$newArray = array();
for ($i = 0; $i<=n; $i++) {
foreach($oldArray[$i] as $key => $value) {
if ($key === 'itemID') {
$a = $key . '" => "' . $value . '",';
}
elseif($key === 'specID') {
$b = '"' . $key . '" => "';
}
elseif($key === 'spec') {
$c = $value;
}
}
$newArray[] = [$a.$b.$c];
}
Maybe I'm completely wrong here, so any help would be greatly appreciated - Thanks!

Answer 1

This table structure is great if the number of item parameters is variable.
The simplest approach is the following:
$array1 = array(...); // from table 1
$array2 = array(...); // from table 2
$result = array();
foreach ($array1 AS $v) {
$result[ $v['itemID'] ] = $v;
}
foreach ($array2 AS $v) {
$result[ $v['itemID'] ][ $v['specId'] ] = $v['spec'];
}

Answer 2

Consider using group_concat
This will fetch everything you need in 1 query:
select items.itemID,
group_concat(concat(specs.specID,":",specs.spec)) as properties
from items join specs on items.itemID=specs.itemID
group by items.itemID;
Results will look like this:
+--------+-------------------------------+
| itemID | properties |
+--------+-------------------------------+
| 1 | color:red,weight:10,price:499 |
| 2 | color:blue |
+--------+-------------------------------+
I'll leave it to you to populate the array but it should be trivial using explode first with "," delimiter then with ":"