> > From: Bennett Haselton
> >
> > My databases textbook from college says that specifying an
> > attribute as an
> > "index" means that the data will be stored in such a way that
> > lookups on
> > that attribute are faster, and specifying an attribute as a
> > "key" means
> > that its values have to be unique.
>
> If you are quoting your textbook correctly I believe it is simply
> wrong (or at least not conveying long accepted ideas).
<cut>
Quoting "SQL-99 Complete, Really!":
----
KEY [1] In standard SQL terminology: a set of Columns in a Table,
whose values ("key values") are unique when taken together...
[2] In everyday speech: a set of not-necessarily-unique values,
especially values stored in indexes ... which can be used to
search particular rows of a Table. Both [1] and [2] are acceptable...
----
/ Carsten
--
Carsten H. Pedersen
keeper and maintainer of the bitbybit.dk MySQL FAQ
http://www.bitbybit.dk/mysqlfaq
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