tree:'id.#'                                                                    ++- "integer"           
tree:'parent_id.#'                                                             ++- "integer"           
tree:'name.#'                                                                  ++- "string : not null" 

tree:'+1':'id.#'                                                               ++- "primary key"       
tree:'+1':'parent_id.#'                                                        ++- "key"               