/**
  * get content sequences for single container or array of ids
  * 
  * @param array|integer|Tinebase_Model_Container $containerIds
  * @return array with key = container id / value = content seq number | integer
  */
 public function getContentSequence($containerIds)
 {
     if (empty($containerIds)) {
         return NULL;
     }
     $containerIds = !is_array($containerIds) ? Tinebase_Model_Container::convertContainerIdToInt($containerIds) : $containerIds;
     $select = $this->_getSelect(array('id', 'content_seq'), TRUE);
     $select->where($this->_db->quoteInto($this->_db->quoteIdentifier('id') . ' IN (?)', (array) $containerIds));
     $stmt = $this->_db->query('/*' . __FUNCTION__ . '*/' . $select);
     $result = $stmt->fetchAll();
     foreach ($result as $key => $value) {
         $result[$value['id']] = $value['content_seq'];
     }
     $result = is_array($containerIds) ? $result : (isset($result[$containerIds]) ? $result[$containerIds] : NULL);
     return $result;
 }