Nette\Database\Table\Selection::execute PHP Method

    protected function execute()
    {
        if ($this->rows !== NULL) {
            return;
        }
        $this->observeCache = $this;
        if ($this->primary === NULL && $this->sqlBuilder->getSelect() === NULL) {
            throw new Nette\InvalidStateException('Table with no primary key requires an explicit select clause.');
        }
        try {
            $result = $this->query($this->getSql());
        } catch (Nette\Database\DriverException $exception) {
            if (!$this->sqlBuilder->getSelect() && $this->previousAccessedColumns) {
                $this->previousAccessedColumns = FALSE;
                $this->accessedColumns = [];
                $result = $this->query($this->getSql());
            } else {
                throw $exception;
            }
        }
        $this->rows = [];
        $usedPrimary = TRUE;
        foreach ($result->getPdoStatement() as $key => $row) {
            $row = $this->createRow($result->normalizeRow($row));
            $primary = $row->getSignature(FALSE);
            $usedPrimary = $usedPrimary && (string) $primary !== '';
            $this->rows[$usedPrimary ? $primary : $key] = $row;
        }
        $this->data = $this->rows;
        if ($usedPrimary && $this->accessedColumns !== FALSE) {
            foreach ((array) $this->primary as $primary) {
                $this->accessedColumns[$primary] = TRUE;
            }
        }
    }

 protected function execute()
 {
     if ($this->rows !== NULL) {
         return;
     }
     parent::execute();
     $this->onExecute();
 }