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Re^2: Tree Structure and Db

by simonm (Vicar)
on Jul 06, 2005 at 16:26 UTC ( #472867=note: print w/replies, xml ) Need Help??


in reply to Re: Tree Structure and Db
in thread Tree Structure and Db

In a tree-wise data structure, with only one parent per child, what is the perceived advantage of using this linking table rather than just adding the parent ID to the main table?

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Re^3: Tree Structure and Db
by (anonymized user) (Curate) on Jul 07, 2005 at 11:18 UTC
    A link table is the normal way to enforce referential integrity in many to many relationships (0 or 1 counts as many for these purposes) and in this case prevents orphans; it also enables you to define different types of relationship without putting more illegal or awkwardly-implemented constraints (and adding maybe-null foreign keys for them) on the master table.

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