docs: change sample code to be more practical

Author: kenjis

user_guide_src/source/database/events.rst

@@ -21,6 +21,8 @@ DBQuery
 This event is triggered whenever a new query has been run, whether successful or not. The only parameter is
 a :doc:`Query </database/queries>` instance of the current query. You could use this to display all queries
 in STDOUT, or logging to a file, or even creating tools to do automatic query analysis to help you spot
-potentially missing indexes, slow queries, etc. An example usage might be:
+potentially missing indexes, slow queries, etc.
+
+An example usage might be:
 
 .. literalinclude:: events/001.php

user_guide_src/source/database/events/001.php

@@ -1,4 +1,18 @@
 <?php
 
 // In app/Config/Events.php
-Events::on('DBQuery', 'CodeIgniter\Debug\Toolbar\Collectors\Database::collect');
+
+namespace Config;
+
+use CodeIgniter\Events\Events;
+use CodeIgniter\Exceptions\FrameworkException;
+use CodeIgniter\HotReloader\HotReloader;
+
+// ...
+
+Events::on(
+    'DBQuery',
+    static function (\CodeIgniter\Database\Query $query) {
+        log_message('info', (string) $query);
+    }
+);