Merge pull request #6935 from kenjis/fix-docs-query_builder

docs: fix query_builder sample code

Author: kenjis

user_guide_src/source/database/query_builder/103.php

@@ -1,11 +1,10 @@
 <?php
 
-$union   = $this->db->table('users')->select('id', 'name');
-$builder = $this->db->table('users')->select('id', 'name');
-
-$builder->union($union)->limit(10)->get();
+$builder = $db->table('users')->select('id, name')->limit(10);
+$union   = $db->table('groups')->select('id, name');
+$builder->union($union)->get();
 /*
  * Produces:
  * SELECT * FROM (SELECT `id`, `name` FROM `users` LIMIT 10) uwrp0
- * UNION SELECT * FROM (SELECT `id`, `name` FROM `users`) uwrp1
+ * UNION SELECT * FROM (SELECT `id`, `name` FROM `groups`) uwrp1
  */

user_guide_src/source/database/query_builder/104.php

@@ -1,9 +1,9 @@
 <?php
 
-$union   = $this->db->table('users')->select('id', 'name')->orderBy('id', 'DESC')->limit(5);
-$builder = $this->db->table('users')->select('id', 'name')->orderBy('id', 'ASC')->limit(5)->union($union);
+$union   = $db->table('users')->select('id, name')->orderBy('id', 'DESC')->limit(5);
+$builder = $db->table('users')->select('id, name')->orderBy('id', 'ASC')->limit(5)->union($union);
 
-$this->db->newQuery()->fromSubquery($builder, 'q')->orderBy('id', 'DESC')->get();
+$db->newQuery()->fromSubquery($builder, 'q')->orderBy('id', 'DESC')->get();
 /*
  * Produces:
  * SELECT * FROM (