	public function update_groupdiscounts() {
	    global $db;

	    if (empty($this->params['id'])) {
	        // look for existing discounts for the same group
	        $existing_id = $db->selectValue('groupdiscounts', 'id', 'group_id='.$this->params['group_id']);
	        if (!empty($existing_id)) flashAndFlow('error',gt('There is already a discount for that group.'));
	    }

        $gd = new groupdiscounts();
	    $gd->update($this->params);
	    expHistory::back();
	}
The software constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.