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Normalization

A poor logical database design can impair the performance of the entire system. Database normalization is a way to eliminate unnecessary duplication and provide a rapid search path to all necessary information. It is a process of refining tables, keys, columns, and relationships to create an efficient database.

A greater number of tables with fewer columns is characteristic of a normalized database. A few wide tables with more columns is characteristic of an non-normalized database.

Benefits of normalization are:

Data integrity

Optimized and faster queries

Fewer null values and less opportunity for inconsistency

Faster index creation and sorting

Faster UPDATE performance

Normalization rules

You can normalize most simple databases by following a simple rule: tables that contain repeated information should be divided into separate tables to eliminate the duplication.

There are a few rules that can help you achieve a sound database design:

A table should have an identifier. Each table should have a unique row identifier, a column or set of columns used to distinguish any single record from every other record in the table. Each table should have an ID column, and no two records can share the same ID value.

A table should avoid nullable columns.

Null values increase the complexity of data operations. If you have a table with several nullable columns and several of the rows have null values in the columns, you should consider placing these columns in another table linked to the primary table.

A table should not have repeating values or columns. The table for an item in the database should not contain a list of values for a specific piece of information.

A table should store only data for a single type of object. Each table should describe only one object. For example, a Customers table will have information about the customers. Attempting to store too much information in a table and to store information irrelevant to the main object can prevent the efficient and reliable management of the data in the table.


Related Topics:

About designing a database

Database performance

Creating a new database

Create a table

How to create a database

About Create Database Wizard

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