Illustrates the term natural key in Sybase

Question

Illustrates the term natural key in Sybase?

Answer 1

Assume the database class... okay, I can't think which far therefore, a natural key is a key for a specified table which uniquely identifies the row. It's natural within the sense that this follows the business or real world require. For illustration, assume that social security numbers are unique then when you had the following worker table:

employee:
ssn char (08)
f_name char(19)
l_name char(19)
title char (02)

After that a natural key would be ssn. When the combination of _name and l_name were unique on this company, then other natural key would be f_name, l_name. Like a matter of fact, you can have several natural keys in a specified table but in practice what one does is build an artificial or (surrogate) key.

The surrogate key is certain to be unique since (wait, get back, now it goes again) it's classically a monotonically increasing value. Probably, my mathematician wife would be proud of me... actually all this means is that the key is raising linearly as: i+1