code: public function execute()
      {
          $this->preExecute();
          $result = $this->connection->query($this->getSql());
          $this->postExecute();
  
          $schemas = array();
          foreach ($result as $row) {
              $schemas[] = new Schema($row['schema_name']);
          }
  
          return $schemas;
      }
docs: {@inheritdoc}