Howto do a recursive query?

Hi I have a set of data organised into a treelike structure. I have to be able to do a query like this to the data: Given a node in the tree, show me all nodes that are in the subtree below the given node. I was thinking about storing the data and the treestructure in a table like: CREATE TABLE LinkTree ( NodeNo SERIAL, ParentNode INTEGER, Info VARCHAR(10), PRIMARY KEY (NodeNo), FOREIGN KEY (ParentNode) REFERENCES LinkTree(ParentNode) ); that is, each node would be given a number and the children of that node would have a pointer to the parent. Using this structure I should be able to select all nodes that have the given node as a parent, and then recursively execute this query again with using all the NodeNo from the query as the given node. The query should terminate when a query returns an empty result set. Does this make any sense at all? If so, how should I create something like this? I realise that I have to use SPL, this wont be a oneliner in standard SQL :) I somehow feel that recursion does not fit into the relational model. I'm implementing this in IUS, does it have any features I should take advantage of? TIA Hrafnkell -- //-----------------------//------------------------------------------------- // Hrafnkell Eiriksson // Student of Computer- and Electrical engineering // hkelle@rhi.hi.is // at the Univeristy of Iceland // // "Blessed are they who go around in circles, // Finger for PGP key // for they shall be known as Wheels"