modelling trees or graphs SQL: how to separate properties of nodes and nodes information

I'm modelling a conceptual ontology like a polytree.

Using the edge list model it would be:

CREATE TABLE nodes(
  nodeID CHAR(1) PRIMARY KEY
);

CREATE TABLE edges(
  childID CHAR(1) NOT NULL,
  parentID CH开发者_JS百科AR(1) NOT NULL,
  PRIMARY KEY(childID,parentID)
);

My problem is how can I model it in SQL so that nodes can have other properties like "types". Eg.

(father-node) **Music**  

has

(child-node) **jazz** [type: genre], **soul** [type: genre]
(child-node) **concert** [type: performed], **DJ set** [type: performed]

You should check out Celkos nested set model, http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/

But anyway just add genre id to your nodes table

CREATE TABLE nodes(
  nodeID CHAR(1) PRIMARY KEY
  genre_id
);