The standard approach, despite the temptation to just use one table with an auto-foreign key, is:
CREATE TABLE node (node_name VARCHAR(32) NOT NULL)

CREATE TABLE node_node ( parent_fk VARCHAR(32) NOT NULL, child_fk VARC
+HAR(32) NOT NULL )

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The next bit is DBMS specific but you also need to define the primary keys: (node.node_name) and (node_node.parent_fk, node_node.child_fk) and the foreign key constraints: node.node_name -> node_node.parent_fk and node.node_name -> node_node.child_fk.

The advantage of this over the single table solution is that it is normalised and can be extended into a multi-type, multi-tree model without having to keep adding foreign keys to the master table.

In reply to Re: Trees in SQL, adjacency lists and sorting. by DungeonKeeper
in thread Trees in SQL, adjacency lists and sorting. by BUU

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