Hi this is the code to save the params of a component, module or plugin in Joomla.
It first loads the current params, makes its changes, then saves again; ensure you always load the current params first.
$mparams = JComponentHelper::getParams( 'com_littlehelper' );
$params = $mparams->get('params');
$mparams->set('params.favicons_sourcepath','icons');
$this->saveParams($mparams, $this->componentName);
private function saveParams($params, $extensionName, $type='component') {
$db = JFactory::getDBO();
$query = $db->getQuery(true);
$query->update('#__extensions AS a');
$query->set('a.params = ' . $db->quote((string)$params));
$query->where(sprintf('a.element = %s AND a.%s = %s',
$db->quote($extensionName),
$db->quoteName('type'),
$db->quote($type)
));
$db->setQuery($query);
return $db->execute();
}
This code comes from my extension LittleHelper published on the JED.