CS计算机代考程序代写 database Hive 2021/8/8 Unnormalized form - Wikipedia

2021/8/8 Unnormalized form – Wikipedia

https://en.wikipedia.org/wiki/Unnormalized_form 1/3

Unnormalized form
In database normalization Unnormalized form (UNF), also known as an unnormalized relation or
non first normal form (N1NF or NF2),[1] is a database data model (organization of data in a database)
which does meet any of the conditions of database normalization defined by the relational model.
Database systems which support unnormalized data is sometimes called non-relational or NoSQL
databases. In the relational model, unnormalized relations can be considered the starting point for a
process of normalization. It should not be confused with denormalization, where normalization is
deliberately compromised for selected tables in a relational database.

History

Relational form

Example

Modern applications

See also

References

In 1970, E.F. Codd proposed the relational data model, now widely accepted as the standard data
model.[2] At that time, office automation was the major use of data storage systems, which resulted in the
proposal of many NF2 data models like the Schek model, Jaeschke models (non-recursive and recursive
algebra), and the Nested Table Data (NTD) model.[1] IBM organized the first international workshop
exclusively on this topic in 1987 which was held in Darmstadt, Germany.[1] Moreover, a lot of research
has been done and journals have been published to address the shortcomings of the relational model.
Since the turn of the century, NoSQL databases have become popular owing to the demands of Web 2.0.

Normalization to first normal form requires the initial data to be viewed as relations.[3] In database
systems relations are represented as tables. The relation view implies some constraints on the tables:

No duplicate rows. In practice, this is ensured by defining one or more columns as primary

keys.

Rows do not have an intrinsic order. While tables have to be stored and presented in some

order, this is unstable and implementation dependent. If a specific ordering need to be

represented, it has to be in the form of data, e.g. a “number” column.

Columns have unique names within the same table.

Contents

History

Relational form

https://en.wikipedia.org/wiki/Database_normalization
https://en.wikipedia.org/wiki/Database
https://en.wikipedia.org/wiki/Data_model
https://en.wikipedia.org/wiki/Relational_model
https://en.wikipedia.org/wiki/NoSQL
https://en.wikipedia.org/wiki/Denormalization
https://en.wikipedia.org/wiki/Edgar_F._Codd
https://en.wikipedia.org/wiki/Relational_model
https://en.wikipedia.org/wiki/Office_automation
https://en.wikipedia.org/wiki/IBM
https://en.wikipedia.org/wiki/Darmstadt
https://en.wikipedia.org/wiki/Relational_model
https://en.wikipedia.org/wiki/NoSQL
https://en.wikipedia.org/wiki/Web_2.0
https://en.wikipedia.org/wiki/First_normal_form
https://en.wikipedia.org/wiki/Relation_(database)
https://en.wikipedia.org/wiki/Primary_keys

2021/8/8 Unnormalized form – Wikipedia

https://en.wikipedia.org/wiki/Unnormalized_form 2/3

Each column has a domain (or data type) which defines the allowed values in the column.

All rows in a table have the same set of columns.

This definition does not preclude columns having sets or relations as values, e.g. nested tables. This is the
major difference to first normal form.

NoSQL databases like Document databases typically does not conform to the relational view. For
example an JSON or XML database might support duplicate records and intrinsic ordering. Such
database can be described as non-relational. But there are also database models which support the
relational view, but does not embrace first normal form.[4] Such models are called non-first normal form
relations (abbreviated NFR, N1NF or NF2).

Customer Cust. ID Transactions

Abraham 1

Tr. ID Date Amount

12890 14-Oct-2003 −87

12904 15-Oct-2003 −50

Isaac 2
Tr. ID Date Amount

12898 14-Oct-2003 −21

Jacob 3

Tr. ID Date Amount

12907 15-Oct-2003 −18

14920 20-Nov-2003 −70

15003 27-Nov-2003 −60

This table represent a relation where one of the columns (Transactions) is itself relation-valued. This is a
valid relation but does not conform to first normal form which does not allow nested relations. The table
is therefore unnormalized.

Today, companies like Google, Amazon and Facebook deal with large amounts of data that are difficult to
store efficiently. They use NoSQL databases, which are based on the principles of the unnormalized
relational model, to deal with the storage issue.[5] Some examples of NoSQL databases are MongoDB,
Apache Cassandra and Redis. These databases are more scalable and easier to query with as they do not
involve expensive operations like JOIN.

Example

Modern applications

https://en.wikipedia.org/wiki/First_normal_form
https://en.wikipedia.org/wiki/NoSQL
https://en.wikipedia.org/wiki/Document_database
https://en.wikipedia.org/wiki/First_normal_form
https://en.wikipedia.org/wiki/First_normal_form
https://en.wikipedia.org/wiki/Google
https://en.wikipedia.org/wiki/Amazon.com
https://en.wikipedia.org/wiki/Facebook
https://en.wikipedia.org/wiki/NoSQL
https://en.wikipedia.org/wiki/NoSQL
https://en.wikipedia.org/wiki/MongoDB
https://en.wikipedia.org/wiki/Apache_Cassandra
https://en.wikipedia.org/wiki/Redis
https://en.wikipedia.org/wiki/Scalability
https://en.wikipedia.org/wiki/Join_(SQL)

2021/8/8 Unnormalized form – Wikipedia

https://en.wikipedia.org/wiki/Unnormalized_form 3/3

Denormalization

Normalization

First normal form

Second normal form

Boyce–Codd normal form

Third normal form

NoSQL

1. Kitagawa, Hiroyuki; Kunii, Tosiyasu L. (1990-02-06). The Unnormalized Relational Data Model.
pp. 1, 5, 7, 10. ISBN 978-4-431-70049-4.

2. “IBM Archives: Edgar F. Codd” (https://www-03.ibm.com/ibm/history/exhibits/builders/builder
s_codd.html). April 23, 2003.

3. Codd, E.F. (1970). A Relational Model of Data for. Large Shared Data Banks. IBM Research
Laboratory, San Jose, California.

4. Operations and the Properties on Non-First-Normal-Form Relational Databases H. Arisawa, K.
Moriya, T. Miura Published in VLDB 1983

5. Moniruzzaman, A B M; Hossain, Syed Akhter (2013). “NoSQL Database: New Era of Databases
for Big data Analytics – Classification, Characteristics and Comparison”. International Journal
of Database Theory and Application. 6.

Retrieved from “https://en.wikipedia.org/w/index.php?title=Unnormalized_form&oldid=1034373502”

This page was last edited on 19 July 2021, at 13:46 (UTC).

Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using

this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia

Foundation, Inc., a non-profit organization.

Related Posts