code: public function deleteFromDB()
    {
      // first check if keys are available
      if (!$this->isValid()) {
        return false;
      }
      
      if(count($this->key_properties)==0){
        // cannot delete without keys
        return false;
      }
      // build where part
      $where_part='';
      foreach ($this->key_properties as $key) {
        if ($where_part) {
          $where_part.=' AND ';
        }
        if ($this->{$key} instanceof Web2All_Table_SQLOperation) {
          trigger_error('Web2All_Table_SaveObjectTrait->deleteFromDB(): using Web2All_Table_SQLOperation object for key value '.$key,E_USER_NOTICE);
          $where_part.=$this->obj_to_db_trans[$key].'='.$this->{$key}->toSQLString();
  
        }else if ($this->{$key} instanceof Web2All_Table_SQLOperationList) {
          throw new Exception("Web2All_Table_SaveObjectTrait: can't delete using a Web2All_Table_SQLOperationList for key value ".$key);
          
        }else{
          $where_part.=$this->obj_to_db_trans[$key].'='.$this->db->Quote($this->{$key});
        }
      }
      
      $this->db->Execute('DELETE FROM '.$this->quote($this->tablename).' WHERE '.$where_part.' ');
      
      return true;
    }
docs: Delete the current object from the database.
  
  It is required that all key properties are set.
  
  @return boolean