generating a parent/child relationship in a trigger

Suppose I'm adding row to a table, and one of the columns is
a pathname.

I would like to generate in a separate table parent/child
relationships based on the path.

For example, adding "/foo/bar/baz" and "/foo/bar/bot" would
generate the following relationships

parent      child
------      -----
/foo        /foo/bar
/foo/bar    /foo/bar/baz
/foo/bar    /foo/bar/bot

Is this a reasonable thing to do in a trigger?  Does anybody
have a pl/sql snippet to do this?

Many TIA,
Mark

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Mark Harrison
Pixar Animation Studios