Elegant eloquent solution

It boils down to fetching items within 2 dates, so I would create a scope for the Item model that filters by created_at between a starting and an ending date.

You could then add some other methods to simplify its usage, like, if you want to get items that came between a given transaction and the next, it would be useful to get it with something like:

$items = Items::duringTransacion($transaction);
// or
$items = $transaction->itemsUntilNext();

Both of these would use a similar implementation. Here is an example of the latter:

class Transaction extends Model
{
    // ...

    public function itemsUntilNext()
    {
        // Fetch relevant dates
        $startDate = $this->created_at;
        $endDate = static::where('created_at', '>', $startDate)
            ->orderBy('created_at')
            ->first()
            ->pluck('created_at');
        
        // Get items using Items::scopeCreatedWithin($start, $end)
        return Item::createdWithin($startDate, $endDate)
            ->get();
    }
}

Thank you for your help, works great! The idea of returning a collection of other models is new to me - very elegant.

Just use slice() to rip off the first enty when retrieving the list:

$transactions = Transaction::orderByDesc('created_at')
        ->get()
        ->slice(0, -1);

Todo: create a scope...

class Transaction extends Model
{
// ...
    public function previousItemDate()
    {
        $endDate = $this->created_at;
        $startDate = static::where('created_at', '<', $endDate)
            ->orderByDesc('created_at')
            ->first()
            ->created_at;

        return $startDate;
    }

    public function previousItems()
    {
        $endDate = $this->created_at;
        $startDate = $this->previousItemDate();

        return Item::whereBetween('itemdate', [$startDate, $endDate])
            ->get();
    }

}