select queries in drupal 8

select queries in drupal 8

  // get all Course Ratings.
  function getCourseRatings($groupId) {
  	// Query to get all ratings for  the course.
	$query = \Drupal::database()->select('attendance__field_course', 'afc');
	$query->join("votingapi_result", "vr", "vr.entity_id = afc.entity_id");
	$query->fields('vr', ['value']);
	$query->condition('vr.function', 'vote_sum');
 	$query->condition('afc.field_course_target_id', $groupId);
	$courseRatings = $query->execute()->fetchAll(\PDO::FETCH_ASSOC);
	return $courseRatings;
  }

  // Sum of votes.
  function getSumOfVotes($groupId) {
	// Sum of votes
	$query = \Drupal::database()->select('attendance__field_course', 'afc');
	$query->join("votingapi_result", "vr", "vr.entity_id = afc.entity_id");
	$query->addExpression("sum(vr.value)", 'sum_votes');
	$query->condition('vr.function', 'vote_sum');
	$query->condition('afc.field_course_target_id', $groupId);
	$sumOfVotes = $query->execute()->fetchField();
	return $sumOfVotes;
  }

  // get all Course Ratings.
  function getCourseRatingsStatistics($groupId) {
	$query = \Drupal::database()->select('attendance__field_course', 'afc');
	$query->join("votingapi_result", "vr", "vr.entity_id = afc.entity_id");
	$query->fields('vr', ['value']);
	$query->condition('vr.function', 'vote_sum');
 	$query->condition('afc.field_course_target_id', $groupId);
    $query->groupBy("vr.value");
    $query->addExpression("COUNT(*)", 'total_votes');
    $result  = $query->execute()->fetchAllKeyed();
    return $result;
  }
  
  // fetch single row 
      $query = \Drupal::database()->select('votingapi_result', 'vr');
    $query->addField('vr', 'value');
    $query->condition('vr.function', 'vote_sum');
    $query->condition('vr.entity_id', $attendanceId);
    $ratings = $query->execute()->fetchField();
    return $ratings;

// DB or conditions
  $query = \Drupal::database()->select('users_field_data', 'ufd');
   $query->fields('ufd', array('uid', 'name', 'mail', 'access', 'created', 'status'));
      /**                                                                                                                                      
       *  (access not 0 and login not 0 and ufd.created  ) or (created < current time - notifytime)                                            
       */
      $orandcond1 = db_and()->condition('ufd.access', 0, '!=')
        ->condition('ufd.login', 0, '!=')
        ->condition('ufd.access', (time() - $notify_time), '<');
      $orandcond2 = db_and()->condition('ufd.login', 0, '=')
        ->condition('ufd.created', (time() - $notify_time), '<');
      $condition = db_or()->condition($orandcond1)->condition($orandcond2);
      $query->condition($condition);
      /**                                                                                                                                      
       *  Active user and not an admin.                                                                                                        
       */
      $query->condition('ufd.uid', 1, '!=');
      $query->condition('ufd.status', 1, '=');
      $result = $query->execute()->fetchAll();