diff -u b/dbtng_example/dbtng_example.module b/dbtng_example/dbtng_example.module
--- b/dbtng_example/dbtng_example.module
+++ b/dbtng_example/dbtng_example.module
@@ -346,7 +346,7 @@
       break;
 
     case 'examples/dbtng/grouping_list':
-      $output = t('Generate a list of all entries in the database in a group. The records will be displayed in grouping format for column "age".');
+      $output = t('Groups the result set by the specified field and render a list of entries in the database. The records will be displayed in grouping format for column "age".');
       break;
   }
   return $output;
@@ -395,7 +395,7 @@
   $items['examples/dbtng/grouping_list'] = array(
     'title' => 'Grouping list',
     'page callback' => 'dbtng_example_grouping_list',
-    'access arguments' => array('access dbtng example grouping list'),
+    'access arguments' => array('access administration pages'),
     'type' => MENU_LOCAL_TASK,
   );
 
@@ -403,22 +403,6 @@
 }
 
 /**
- * Implements hook_permission().
- *
- * This hook can supply permissions that the module defines, so that they can
- * be selected on the user permissions page and used to grant or restrict
- * access to actions the module performs.
- */
-function dbtng_example_permission() {
-  return array(
-    'access dbtng example grouping list' => array(
-      'title' => t('Permission to view Grouping List'),
-      'description' => t('Give permission to access Grouping List.'),
-    ),
-  );
-}
-
-/**
  * Render a list of entries in the database.
  */
 function dbtng_example_list() {
@@ -604,37 +588,51 @@
 /**
  * This function groups the result set by the specified field and render a
  * list of entries in the database
- *
+ */
+function dbtng_example_grouping_list() {
+  $result = dbtng_example_execute_group_by_select_query();
+  return dbtng_example_render_resultset_as_table($result);
+}
+
+/**
+ * The code below will result in the following query
  * SELECT ex.pid AS pid, ex.uid AS uid, ex.name AS name, ex.surname AS surname,
  * ex.age AS age FROM {dbtng_example} ex GROUP BY ex.age
- *
  */
-function dbtng_example_grouping_list() {
+function dbtng_example_execute_group_by_select_query() {
   $dbtng_example_execute_group_by_select_query = db_select('dbtng_example', 'ex')->fields('ex');
   // 'ex.age' is the field on which to group
   $dbtng_example_execute_group_by_select_query->groupBy('ex.age');
   // generate the result in object format.
   $dbtng_example_result = $dbtng_example_execute_group_by_select_query->execute()->fetchAll();
-  $output = '';
-  if ($dbtng_example_result) {
-    foreach ($dbtng_example_result as $row) {
+  return $dbtng_example_result;
+}
+
+/**
+ * This function renders a resultset as table
+ */
+function dbtng_example_render_resultset_as_table($result) {
+  $rows = array();
+  if ($result) {
+    foreach ($result as $row) {
       // Sanitize the data before handing it off to the theme layer.
       $rows[] = array_map('check_plain', (array) $row);
     }
-    $output .= dbtng_example_render_resultset_as_table($rows);
-  }
-  else {
-    drupal_set_message(t('No records found.'));
   }
-  return $output;
+  return dbtng_example_convert_resultset_to_table_render_array($rows);
 }
 
-function dbtng_example_render_resultset_as_table($rows = array()) {
-  // Make a table.
+/**
+ * This function renders array for table 'dbtng_example'
+ */
+function dbtng_example_convert_resultset_to_table_render_array($rows = array()) {
   $header = array(t('Id'), t('uid'), t('Name'), t('Surname'), t('Age'));
-  $output = theme('table', array('header' => $header, 'rows' => $rows));
-
-  return $output;
+  return [
+    '#theme' => 'table',
+    '#header' => $header,
+    '#rows' => $rows,
+    '#empty' => t('No records found'),
+  ];
 }
 /**
  * @} End of "defgroup dbtng_example".