code: private function getColumnComments()
      {
          $escapement = new Escapement();
          $comments = '';
          foreach ($this->table->getColumns() as $column) {
               $columnDescription = $column->getDescription();
               if (!empty($columnDescription)) {
                  $comments .= sprintf("COMMENT ON COLUMN %s.%s IS '%s';",
                      $escapement->escape($this->table->getQualifiedName()),
                      $escapement->escape($column->getName()),
                      $columnDescription);
               }
          }
  
          return $comments;
      }
docs: Gets comments for columns.
  
  @return string