O'Reilly logo

Data Modeling Made Simple: A Practical Guide for Business and IT Professionals by Steve Hoberman

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

CHAPTER 7 What are keys?

More than one John DoeWhich is the right Customer?Recall by the key

There is a lot of data out there, but how do you sift through it all to find what you’re looking for? That’s where keys come in. A key is one or more attributes whose purposes include enforcing rules, efficiently retrieving data, and allowing navigation from one entity to another. This chapter defines keys and distinguishes between the terms candidate, primary, and alternate keys. Surrogate keys and foreign keys and their importance are also explained.

Candidate Key (Primary and Alternate) Explained

A candidate key is one or more attributes that uniquely identify an entity instance. An ISBN (International Standard Book Number) is assigned to every title. ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required