improve sync daily changes command

app/Models/Holding.php

@@ -8,7 +8,6 @@ use App\Models\Portfolio;
 use App\Models\MarketData;
 use App\Models\Transaction;
 use Illuminate\Support\Facades\DB;
-use Illuminate\Support\Facades\Log;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Concerns\HasUuids;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
@@ -255,7 +254,18 @@ class Holding extends Model
                 COALESCE(SUM(CASE WHEN transactions.transaction_type = 'BUY' THEN transactions.quantity ELSE 0 END), 0) -
                 COALESCE(SUM(CASE WHEN transactions.transaction_type = 'SELL' THEN transactions.quantity ELSE 0 END), 0) AS `owned`
             "),
-            DB::raw("COALESCE(SUM(CASE WHEN transaction_type = 'BUY' THEN (quantity * cost_basis) ELSE 0 END), 0) AS `cost_basis`"),
+            DB::raw("
+               COALESCE(CASE 
+                    WHEN (
+                        COALESCE(SUM(CASE WHEN transactions.transaction_type = 'BUY' THEN transactions.quantity ELSE 0 END), 0) - 
+                        COALESCE(SUM(CASE WHEN transactions.transaction_type = 'SELL' THEN transactions.quantity ELSE 0 END), 0)
+                    ) = 0 THEN 0
+                    ELSE SUM(CASE 
+                        WHEN transactions.transaction_type = 'BUY' THEN transactions.quantity * transactions.cost_basis 
+                        ELSE 0 
+                    END)
+                END, 0) AS cost_basis
+            "),
             DB::raw("COALESCE(SUM(CASE WHEN transaction_type = 'SELL' THEN ((sale_price - cost_basis) * quantity) ELSE 0 END), 0) AS `realized_gains`")
         ])
         ->leftJoin('transactions', function ($join) {