Re: Nested Sets vs. Nested Intervals

amado.alves_at_netcabo.pt wrote:
> In the Dot language (Graphviz from AT&T):
>
> digraph {
> Employees -> x1
> Employees -> x2
> Employees -> x3
> Name -> x4
> Name -> x5
> Name -> x6
> Dept -> x7
> Dept -> x8
> Dept -> x9
> Salary -> x10
> Salary -> x11
> Salary -> x12
> Departments -> x13
> Departments -> x14
> Deptno -> x15
> Deptno -> x16
> Name -> x17
> Name -> x18
> x1 -> x4 -> Smith
> x1 -> x7 -> x13
> x1 -> x10 -> 1000
> x2 -> x5 -> Scott
> x2 -> x8 -> x14
> x2 -> x11 -> 2000
> x3 -> x6 -> King
> x3 -> x9 -> x14
> x3 -> x12 -> 3000
> x13 -> x15 -> 1
> x13 -> x17 -> Accounting
> x14 -> x16 -> 2
> x14 -> x18 -> Manufacturing
> }
>
> Note this is a canonical, literal translation of the given relational
> database. Modelling the semantic domain directly on Mneson would
> simplify things. For example the Deptno is probably not necessary
> semantically but just a requirement of the relational model for a key,
> or for the connection (join), or both. Mneson does not need keys. A
> distinct entity is a distinct vertex. Connected entities simply share a
> topology.

Ok, so literal translation of 2 minuscule relations 3x3 and 2x2 gives a graph with 44 edges. Not bad for a start. And network/hierarchy people are complining that modelling a graph in relational model with a puny

table Edges (

    fromNode integer,
    toNode integer
)

is unwieldy!

Could you please provide a more compact graph (by Nelson, Carson or whatever other semantic metadology) which is perhaps a little bit more impressive? Received on Fri Nov 11 2005 - 04:47:44 CET