what is a primary key

[Guest]

A primary key is a field or fields (sometimes called a
composite key) that is unique (no repeating values) and
used to identify your records in a table. It can be an
autonumber type field, customber id number, whatever, but
it must be unique.

It can be used as a foriegn key in another table to
relate one table to another.

Richard
(e-mail address removed)

 

[Immanuel Sibero]

In addition to uniqeness as mentioned below by previous poster, in a
normalized table, a primary key is also a field or fields which all the
other fields in that table depend on. This dependence is absolute in a sense
that all the other fields in the table depend on, and only on, the primary
key and on nothing else. Uniqueness in a field can certainly make the field
a *key*, but by itself uniqueness is not sufficient to make the field a
primary key. The absolute dependence concept described above makes a field
*primary*.

HTH,
Immanuel Sibero