From 0c61269bcfdabfe654d277525ce684fd637f64a4 Mon Sep 17 00:00:00 2001
From: thinkphp <thinkphp@qq.com>
Date: Wed, 13 Dec 2017 17:54:53 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E6=AD=A3setDec=E6=96=B9=E6=B3=95?=
 =?UTF-8?q?=E7=9A=84=E5=BB=B6=E8=BF=9F=E5=86=99=E5=85=A5?=
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---
 library/think/db/Query.php                     | 1 +
 library/think/model/relation/BelongsToMany.php | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index 64a446a4..0df53610 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -635,6 +635,7 @@ class Query
                 $this->options = [];
                 return true;
             }
+            return $this->setField($field, ['inc', $field, $step]);
         }
         return $this->setField($field, ['dec', $field, $step]);
     }
diff --git a/library/think/model/relation/BelongsToMany.php b/library/think/model/relation/BelongsToMany.php
index f9d69099..13a8018d 100644
--- a/library/think/model/relation/BelongsToMany.php
+++ b/library/think/model/relation/BelongsToMany.php
@@ -53,7 +53,7 @@ class BelongsToMany extends Relation
         $this->query = (new $model)->db();
         $this->pivot = $this->newPivot();
 
-        if (!is_subclass_of($this->pivot, '\\think\\model\\Pivot')) {
+        if ('think\model\Pivot' == get_class($this->pivot)) {
             $this->pivot->name($this->middle);
         }
     }