Codd's 12 Rules for RDBMS

In this tutorial, we will learn about the 12 golden rules of EF-Codd for the database management system (DBMS). By Bharti Parmar Last updated : May 27, 2023

In 1970's DR. EF-Codd published a paper, titled a Relational Model of Data for large shared databases. This paper becomes the all development RDBMS. In support of their relational model, Dr. EF-Codd also proposed 12 rules which are known as 12 golden rules of EF-Codd.

Rule 0: The Foundation Rule

For a system, it must be able to qualify as an RDBMS and to manage its databases entirely through its relational capabilities.

Rule 1: The Information Rule

The data stored in a database (maybe user data or metadata) must be a value of some table cell, everything in a database must be stored in a table format.

Rule 2: The Guaranteed Access Rule

Every single data element value has guaranteed to be accessible logically with a combination of table name, attribute name, primary key. No other means such as pointer can be used to access data.

Rule 3: Systematic Treatment of NULL Values

The null values in the database create an empty cell. This null value in a database must be given a systematic and uniform treatment. This is a very important rule because a null can be interpreted as one of the following: data is missing, data is not known, data is not applicable.

Rule 4: Dynamic Online Catalog Based on the Relational Model

The structure description of the entire database must be stored in an online catalog known as the data dictionary. Which can be accessed by the authorized user. Users can use the same query language to access the catalog which they use to access DB itself.

Rule 5: The Comprehensive Data Sublanguage Rule

A database can be used only be access using language having linear syntax that supports data definition, data manipulation & transaction management operation. This language can be used directly or by means of some application. If the database allows access to data without any help of this language, then it is considering as a violation.

Rule 6: The View Updating Rule

All the views of the database which can theoretically be updated must also be updatable by the system.

Rule 7: High-Level Insert, Update, and Delete Rule

A DB must support high-level insertion, updation, and deletion. This must not the limited to a single row i.e. it must support union, intersection & (-) minus operation to yield sets of data records.

Rule 8: Physical Data Independence

The data stored in a database must be independent of the application that access the database. Any changes in the physical structure of the database must nor have any impact on how the data is being accessed by an external application.

Rule 9: Logical Data Independence

The logical data and database must be independent of its user view application any changes in logical data must not affect the application using it.

Rule 10: Integrating Independence

A database must be independent of the application that uses it. All its integrity constraints can be independently modified without the need of any change in the application.

Rule 11: Distribution Independence

The end user must not be able to see that the data is distributed at the over the various location. Users should always get the impression that the data is located one site only.

Rule 12: The Non-subversion Rule

If a system has an interface that provides access to low-level records then the interface must not be able to bypass security and integrity constraints.


In this, we have learned the 12 golden rules of EF-Codd. I hope you understand the all the 12 rules and the whole concept behind these 12 rules for RDBMS. We will discuss more it. Stay tuned for the next article. Have a nice day! Happy learning!

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