Is it possible to add elements to the 2nd dimension of a multidimensional array without a key in PHP?

I am writing a page that creates Excel reports based on the fields selected. I am using the SimpleXLSXGen class, which requires a 2-level multidimensional array, with each array within the second dimension becoming a row on the Excel sheet. I fetch values using a query and assign the fields to variables.

When I write it like this, all is fine:

while ($row = mysqli_fetch_assoc($query)) {

    $rows[] = [
        $row["field0"], $row["field1"], $row["field2"], $row["field3"], $row["field4"],
        $row["field5"], $row["field6"], $row["field7"], $row["field8"], $row["field9"],
        $row["field10"], $row["field11"], $row["field12"]
    ];
}

but my aim is to populate the array dynamically. When I write something like this:

while ($row = mysqli_fetch_assoc($query)) {

    for ($i = 1; $i < $field_count; $i++) {
        $rows[][] = $row["field" . $i];
    }
}

I end up with a single row that contains all of the elements. This is probably a stupid syntax thing, but I have spent way too much time on this now and I think there must be a way to iterate through a multidimensional array without a key. How can I accomplish this?

>Solution :

Create a new array and add it to the first one:

while ($row = mysqli_fetch_assoc($query)) {
    $item = [];
    for ($i = 1; $i < $field_count; $i++) {
        $item[] = $row["field" . $i];
    }
    $rows[] = $item;
}