I never really took any effort to bother to know what these are until
they got in my way in otherwise fine paper:
http://arxiv.org/PS_cache/arxiv/pdf/...710.2083v1.pdf
It defines an entity as a relation (aka table:-) with a single
noncomposite key, and relationship as a table with composite key. Does
this definition pretty much exhausts the entity-relationship theory?

Tegiri Nenashi wrote:

Um, no, because an order line item is generally an entity--albeit a weak
one. If I recall correctly.