Creating a multidimensional array from database query in PHP

Question

I'm creating an ecommerce site that has products with multiple attributes (size, colour, etc,.) so each attribute also has a number of values (for size these would be: small, medium, large, etc,.)

I have an array of id's representing the attributes like so:

$attributes = [1,2,3];

I then want to query my database for each of those id's to get th values for that attribute and create a multi-dimensional array of the results, like this:

array (size=3)
  1 => size
      0 => 'small'
      1 => 'medium'
      2 => 'large'
  2 => colour
      0 => 'red'
      1 => 'green'
      2 => 'blue'
  3 => pattern
      0 => 'spots'
      1 => 'stripes'
      2 => 'plain'

What I have so far is like this:

$attribute_array = [];
foreach($attributes as $attribute_id){
    $params = [$attribute_id];
    $sql = "SELECT * FROM attributes WHERE attribute_id=?";
    $stmt = DB::run($sql,$params);
    while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
        $attribute_value = $row['attribute_value'];

        //$attribute_array[$attribute_id] = $attribute_value; // this only takes the last value from the last row
        //array_push($attribute_array[$attribute_id],$attribute_value); // this says that the first arg isn't an array
    }
}

What I want to achieve in the end is to get every combination of attributes for a product (small+red+stripes, small+green+stripes, small+blue+stripes, etc,.)

@Jesse thanks for your comment, $attribute_array[$attribute_id] = $row; does the same as $attribute_array[$attribute_id] = $attribute_value; as in adding only the last row, but adds the additional id column as well — Paddy Hallihan
– Paddy Hallihan, Commented Sep 21, 2018 at 16:13

Nigel Ren · Accepted Answer · 2018-09-21 16:12:42Z

1

You were almost there...

$attribute_array[$attribute_id][] = $attribute_value;

note the [] which adds the value to the list of values already there - without it it will just overwrite the previous value.

answered Sep 21, 2018 at 16:12

Nigel Ren

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1 Comment

Paddy Hallihan Over a year ago

Thanks you so much exactly what I was looking for. Will accept you answer a.s.a.p.

Jeffrey Meyer · Accepted Answer · 2018-09-21 16:20:43Z

0

    $attribute_array = [];
    foreach($attributes as $attribute_id){
    $params = [$attribute_id];
    $sql = "SELECT size,colour,pattern,etc FROM attributes WHERE attribute_id=?";
    $stmt = DB::run($sql,$params);
        while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
           // $attribute_value = $row['attribute_value'];
            $attribute_array[] = $row;
        }
    }

Doing this way will return an array of the attributes and store in 0-indexed associative array.

    $attribute_array[0][size,colour,pattern]

Example: $size = $attribute_array[0]['size']

answered Sep 21, 2018 at 16:20

Jeffrey Meyer

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