Database Journal
MS SQL Oracle DB2 Access MySQL PostgreSQL Sybase PHP SQL Etc SQL Scripts & Samples Tips Database Forum Rss Feed

» Database Journal Home
» Database Articles
» Database Tutorials
MS Access
SQL Scripts & Samples
» Database Forum
» Slideshows
Free Newsletters:

News Via RSS Feed

Rss Feed

Database Journal |DBA Support |SQLCourse |SQLCourse2

Featured Database Articles


Posted Jan 28, 2002

Listen Software's How To: Normalization

By David Nishimoto


Following the normalization guidelines usually means splitting tables into two or more tables with fewer columns. Primary and foreign key relationships are designed into the new smaller tables, so they can be reconnected with a join operation. The advantage of splitting the table is to reduce data redundancy. Here's a brief guide to the standard normalization forms:

First Normal Form

At each row and column intersections, there must be one and only one value. Each column in a row can have only one value, and that value must be atomic.

Second Normal Form

Second normal form requires no non-key column be a fact about a subset of the primary key. Event non-key column must depend entirely on the entire primary key. The primary key must have an element of uniqueness. A primary key may be composed of one or more columns forming a unique key. The primary key does not change one created. The foreign key references an tables primary key. The primary to foreign key represents a one to many relationship.

Third Normal Form

Third Normal Forms Requires no non-key column depend on another non-key column.

Fourth Normal Form

Fourth Normal form forbids independent one-to-may relationships between primary key columns and non-key columns.

Fifth Normal Form

Fifth normal form breaks tables into the smallest possible pieces in order to eliminate all redundancy within a table.

David Nishimoto
For Listen Software

Oracle Archives

Latest Forum Threads
Oracle Forum
Topic By Replies Updated
Oracle Data Mining: Classification jan.hasller 0 July 5th, 07:19 AM
Find duplicates - Unique IDs Lava 5 July 2nd, 08:30 AM
no matching unique or primary key rcanter 1 April 25th, 12:32 PM
Update values of one table based on condition of values in other table using Trigger Gladiator 3 February 29th, 06:01 PM