that is not derived from any data in the database and whose
only significance is to act as the primary key.
A surrogate key is frequently a sequential number (e.g. a
the key independent of all other columns insulates the
database relationships from changes in data values or database
design and guarantees uniqueness.
Some database designers use surrogate keys religiously
However, if a good key already exists, the addition of a
surrogate key will merely slow down access, particularly if it
is indexed.
(1999-12-07)