diff --git a/backstage/application/api/models/User_model.php b/backstage/application/api/models/User_model.php
index e1d51d8..471ef61 100644
--- a/backstage/application/api/models/User_model.php
+++ b/backstage/application/api/models/User_model.php
@@ -1178,7 +1178,7 @@ class User_model extends CI_Model
     // 清空指定applet_openid
     public function clearAppletOpenid($openid){
         $this->db->where('applet_openid', $openid);
-        $data = array('applet_openid' => '');
+        $data = array('applet_openid' => null);
         return $this->db->update('tb_user', $data);
     }
 }