diff --git a/app/Http/Controllers/Admin/CourseContentController.php b/app/Http/Controllers/Admin/CourseContentController.php
index e712273..1484b27 100755
--- a/app/Http/Controllers/Admin/CourseContentController.php
+++ b/app/Http/Controllers/Admin/CourseContentController.php
@@ -87,7 +87,7 @@ class CourseContentController extends BaseController
                         // notnull搜索
                         if ($op == 'notnull') {
                             // 不是null并且不是空json，这个是一个json字段
-                            $query->whereNotNull($key)->whereRaw('json_length(' . $key . ') >', 0);
+                            $query->whereNotNull($key)->whereRaw("json_length($key) > 0");
                         }
                         // 范围搜索
                         if ($op == 'range') {