fix bug

biz-hd/product/classes/ProductClass.php

@@ -527,7 +527,7 @@ class ProductClass extends BaseClass
             Yii::$app->redis->executeCommand('HDEL', [$limitKey, $customId]);
         } else {
             $hasNum = Yii::$app->redis->executeCommand('HGET', [$limitKey, $customId]);
-            $remainNum = $hasNum > $num ? bcsub($hasNum - $num) : 0;
+            $remainNum = $hasNum > $num ? bcsub($hasNum, $num) : 0;
             $remainNum = floor($remainNum);
             if ($remainNum > 0) {
                 Yii::$app->redis->executeCommand('HSET', [$limitKey, $customId, $remainNum]);