Re: Problem with Nested Sets

The script below models/queries forums with an experimental db (XDb2).

// Create item in directory to organize things.
(CREATE *forum.item ~in = dir)

// Create verb "contain"

(CREATE *contain.cls = verb)

// Create following forum hierarchy
// Root
// Math
// Algebra
// Trig
// Calculus
// Science
// Physics
// Newtonian
// Quantum
// Chemistry
// Quantum

(CREATE *root.cls = forum
 & it.item ~in = dir
 & it.contain = (CREATE *math.cls = forum

                 & it.contain = (CREATE *algebra.cls = forum)
                 & it.contain = (CREATE *trig.cls = forum)
                 & it.contain = (CREATE *calculus.cls = forum))
 & it.contain = (CREATE *science.cls = forum
                 & it.contain = (CREATE *physics.cls = forum
                                 & it.contain = (CREATE *newtonian.cls
                                                              = forum)
                                 & it.contain = (CREATE *quantum.cls
                                                              = forum))
                 & it.contain = (CREATE *chemistry.cls = forum
                                 & it.contain = (CREATE *quantum.cls
                                                              = forum))
                 & it.contain = (CREATE *geology.cls = forum)))

// Find a forum named quantum.
// Finds the one under physics and the one under chemistry.
(SELECT *.cls = forum & *.name = quantum)

// Find a forum named quantum under physics.
// Finds the one under physics.

(SELECT *.cls = forum & *.name = quantum & physics.contain = *) Received on Tue Feb 22 2005 - 20:17:11 CET