Solved

Need help understanding the second and third normal forms

Posted on 2008-10-22
3
480 Views
Last Modified: 2012-05-05
I have two questions.
(1.) Besides needing to satisfy the first normal form, is the second normal applicable only to enitities/tables that have compound primary keys? Or can it be applicable to a table with only one primary key?

(3) What is the third normal form? Is it basically saying that no Non Key attributes must not be dependent upon each other?

0
Comment
Question by:brgdotnet
  • 2
3 Comments
 
LVL 18

Assisted Solution

by:David Robitaille
David Robitaille earned 30 total points
ID: 22781072
1- It can it be applicable to a table with only one primary key, yes, it<s just remove the "duplicate", the street exemple is good, we got a database where the same street is not always spelled the same.
2 - (or 3) basicly it s that.
 
here some bonus links
http://databases.about.com/od/specificproducts/a/firstnormalform.htm
http://databases.about.com/od/specificproducts/a/2nf.htm
http://databases.about.com/od/specificproducts/a/3nf.htm 
0
 
LVL 22

Accepted Solution

by:
dportas earned 50 total points
ID: 22781277
(1) No. 2NF is a rule that can apply to any relation.
(2) ?
(3) Very loosely speaking you are right.

The most important normal forms are BCNF and 5NF. 2NF and 3NF are somewhat weaker rules about functional dependencies. Since they are subsumed by BCNF it's arguable that 2NF and 3NF are not very important. In fact what many people refer to as 3NF is really BCNF - the definitions are often confused.
0
 
LVL 18

Expert Comment

by:David Robitaille
ID: 22782180
I agree with dportas
0

Featured Post

NAS Cloud Backup Strategies

This article explains backup scenarios when using network storage. We review the so-called “3-2-1 strategy” and summarize the methods you can use to send NAS data to the cloud

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Composite queries are used to retrieve the results from joining multiple queries after applying any filters. UNION, INTERSECT, MINUS, and UNION ALL are some of the operators used to get certain desired results.​
In this article we will learn how to fix  “Cannot install SQL Server 2014 Service Pack 2: Unable to install windows installer msi file” error ?
Familiarize people with the process of utilizing SQL Server functions from within Microsoft Access. Microsoft Access is a very powerful client/server development tool. One of the SQL Server objects that you can interact with from within Microsoft Ac…
Using examples as well as descriptions, and references to Books Online, show the documentation available for datatypes, explain the available data types and show how data can be passed into and out of variables.

809 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question