Florian Boesch wrote:
Table('children', engine,
Column('children_id', Integer, Sequence('children_seq'),
primary_key=True),
Column('tag_node_id', Integer, ForeignKey('tag_node.id'),
nullable=False),
Column('node_id', Integer, ForeignKey('node.id'), nullable=False),
Column('ordering', Integer, nullable=False),
)
I'd prefer to have a list of parent nodes; one of the properties of
these trees is that each node has one parent only (except root, which
has none):
CREATE TABLE parents (
node_id INTEGER NOT NULL REFERENCES node(id),
parent_id INTEGER NOT NULL REFERENCES node(id),
ordering INTEGER NOT NULL,
PRIMARY KEY (node_id, parent_id),
UNIQUE (node_id, ordering) -- probably screwed the syntax here
);
This way, you can select all of a node's children (by checking if it's
referenced in the parent_id column) or select all parents (by getting
the list of parent's for a node).
Thank you once again Mike, for providing that article; I still can't
wrap my brain around it properly, but this model seems quite nice.
--
Luís Bruno
"You see, it's our tears, Stan, that give God his great power."
-- Chef, Southpark
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