FOF30\Model\DataModel::move PHP Method

    public function move($delta, $where = '')
    {
        if (!$this->hasField('ordering')) {
            throw new SpecialColumnMissing(sprintf('%s does not support ordering.', $this->tableName));
        }
        $this->triggerEvent('onBeforeMove', array(&$delta, &$where));
        $ordering_field = $this->getFieldAlias('ordering');
        // If the change is none, do nothing.
        if (empty($delta)) {
            $this->triggerEvent('onAfterMove');
            return $this;
        }
        $k = $this->idFieldName;
        $row = null;
        $db = $this->getDbo();
        $query = $db->getQuery(true);
        // If the table is not loaded, return false
        if (empty($this->{$k})) {
            throw new RecordNotLoaded(sprintf("Model %s does not have a loaded record", $this->getName()));
        }
        // Select the primary key and ordering values from the table.
        $query->select(array($db->qn($this->idFieldName), $db->qn($ordering_field)))->from($db->qn($this->tableName));
        // If the movement delta is negative move the row up.
        if ($delta < 0) {
            $query->where($db->qn($ordering_field) . ' < ' . $db->q((int) $this->{$ordering_field}));
            $query->order($db->qn($ordering_field) . ' DESC');
        } elseif ($delta > 0) {
            $query->where($db->qn($ordering_field) . ' > ' . $db->q((int) $this->{$ordering_field}));
            $query->order($db->qn($ordering_field) . ' ASC');
        }
        // Add the custom WHERE clause if set.
        if ($where) {
            $query->where($where);
        }
        // Select the first row with the criteria.
        $row = $db->setQuery($query, 0, 1)->loadObject();
        // If a row is found, move the item.
        if (!empty($row)) {
            // Update the ordering field for this instance to the row's ordering value.
            $query = $db->getQuery(true)->update($db->qn($this->tableName))->set($db->qn($ordering_field) . ' = ' . $db->q((int) $row->{$ordering_field}))->where($db->qn($k) . ' = ' . $db->q($this->{$k}));
            $db->setQuery($query)->execute();
            // Update the ordering field for the row to this instance's ordering value.
            $query = $db->getQuery(true)->update($db->qn($this->tableName))->set($db->qn($ordering_field) . ' = ' . $db->q((int) $this->{$ordering_field}))->where($db->qn($k) . ' = ' . $db->q($row->{$k}));
            $db->setQuery($query)->execute();
            // Update the instance value.
            $this->{$ordering_field} = $row->{$ordering_field};
        }
        $this->triggerEvent('onAfterMove');
        return $this;
    }