Grouping Array by Value - php

Question

I am looking to group my array into sub arrays when they have the same Supplier ID. I have looked at many similar questions on here but I cannot get any of them to work for me. I have tried foreach loops and even the PHP merge function. I have to use MySQLi for this so I cannot group using PDO.
This is what I have:
Array
(
[supplierID] => 1
[drugID] => 1
[costPrice] => 9.98
[reorderQTY] => 50
)
Array
(
[supplierID] => 1
[drugID] => 2
[costPrice] => 9.98
[reorderQTY] => 50
)
Array
(
[supplierID] => 2
[drugID] => 3
[costPrice] => 9.98
[reorderQTY] => 50
)
This is what I need:
Array
(
[supplierID] => 1
Array
(
[drugID] => 1
[costPrice] => 9.98
[reorderQTY] => 50
)
[drugID] => 2
[costPrice] => 9.98
[reorderQTY] => 50
)
)
Array
(
[supplierID] => 2
Array
(
[drugID] => 3
[costPrice] => 9.98
[reorderQTY] => 50
)
)
This is the PHP where I am outputting the array to get the above result:
if(isset($_POST["automatic"])){
$sql = "SELECT supplierID,drugID,costPrice,reorderQTY FROM drugs WHERE quantityInStock <= reorderLevel";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
// output data of each row
while($row = mysqli_fetch_assoc($result)) {
echo "<pre>";
print_r($row);// I need to sort this array into sub array groups by supplierID key
echo "</pre>";
}
}else{
echo " <tr><td>0 results </td></tr>";
}
mysqli_close($conn);
}

Answer 1

Something like this will do it,
$out = [];
while($row = mysqli_fetch_assoc($result)) {
$out[$row->supplierID][] = $row;
}
Basically I use the supplier id to create an array key, then assign an empty array. Then add all rows with that supplier id to that array.
This will create a multidimensional array.