diff --git a/database/migrations/2026_09_26_150000_add_upgrade_columns_to_invoice_tables.php b/database/migrations/2026_09_26_150000_add_upgrade_columns_to_invoice_tables.php
index c4e7daf..979df71 100644
--- a/database/migrations/2026_09_26_150000_add_upgrade_columns_to_invoice_tables.php
+++ b/database/migrations/2026_09_26_150000_add_upgrade_columns_to_invoice_tables.php
@@ -2,25 +2,18 @@
 
 use Illuminate\Database\Migrations\Migration;
 use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Schema;
 
 return new class extends Migration
 {
     public function up(): void
     {
-        Schema::table('invoices', function (Blueprint $table) {
-            $table->unsignedBigInteger('service_id')->nullable()->after('order_id')->index()
-                  ->comment('Service this invoice upgrades; set for invoice_type=3 (upgrade)');
+        $this->addForeignColumn('invoices', 'service_id', 'order_id', 'services',
+            'Service this invoice upgrades; set for invoice_type=3 (upgrade)');
 
-            $table->foreign('service_id')->references('id')->on('services')->onDelete('set null');
-        });
-
-        Schema::table('invoice_items', function (Blueprint $table) {
-            $table->unsignedBigInteger('addon_id')->nullable()->after('product_id')->index()
-                  ->comment('Addon purchased on this line; set for type=upgrade');
-
-            $table->foreign('addon_id')->references('id')->on('product_addon')->onDelete('set null');
-        });
+        $this->addForeignColumn('invoice_items', 'addon_id', 'product_id', 'product_addon',
+            'Addon purchased on this line; set for type=upgrade');
     }
 
     public function down(): void
@@ -35,4 +28,39 @@ return new class extends Migration
             $table->dropColumn('service_id');
         });
     }
+
+    private function addForeignColumn(string $table, string $column, string $after, string $references, string $comment): void
+    {
+        if (! Schema::hasColumn($table, $column)) {
+            Schema::table($table, function (Blueprint $blueprint) use ($column, $after, $comment) {
+                $blueprint->unsignedBigInteger($column)->nullable()->after($after)->comment($comment);
+            });
+        }
+
+        if (! Schema::hasIndex($table, [$column])) {
+            Schema::table($table, fn (Blueprint $blueprint) => $blueprint->index($column));
+        }
+
+        if (collect(Schema::getForeignKeys($table))->contains(fn ($fk) => $fk['columns'] === [$column])) {
+            return;
+        }
+
+        $this->nullZeroDates($table);
+
+        Schema::table($table, function (Blueprint $blueprint) use ($column, $references) {
+            $blueprint->foreign($column)->references('id')->on($references)->nullOnDelete();
+        });
+    }
+
+    private function nullZeroDates(string $table): void
+    {
+        $dateColumns = collect(Schema::getColumns($table))
+            ->filter(fn ($c) => $c['nullable'] && in_array($c['type_name'], ['date', 'datetime', 'timestamp'], true));
+
+        foreach ($dateColumns as $c) {
+            DB::table($table)
+                ->whereRaw("CAST(`{$c['name']}` AS CHAR) LIKE '0000-%' OR CAST(`{$c['name']}` AS CHAR) LIKE '%-00%'")
+                ->update([$c['name'] => null]);
+        }
+    }
 };