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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? |
Re^3: Tree Structure and Db
by anonymized user 468275 (Curate) on Jul 07, 2005 at 11:18 UTC
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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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