CODD’s Rule In Oracle

Dr. Edgar F. CODD formulated 12 rules for RDBMS in 1970.

In the Relational database model, all the information is represented by the data value in the tables. This means that all table information such as information of table, columns name, view etc. In this rule, access to the data can be restricted and all the information is stored in the tables.

Guaranteed Access

In this Relational database model, every value of the data must be logically addressed, using a combination of the table name, primary key value and the column name.

Systematic Treatment of Null Values

In Relational database model, independent data types and null values are supported for the representation of missing and in applicable information.
For instance, in a system, a character is used to represent missing or in applicable data.

For example:

 

Four permissible values for a column inventory are defined as-
   I               Inventory Present
   INOT       Inventory Not Present
   DN          Data Not Applicable
   NA          Not Applicable

Database Description Rule

In Relational Database model, a description of the database is stored and maintained in the form of table, while defining the data.
This rule allows the user with the authority to query information in the same commands, which are used to access any other table.

Comprehensive Data Sub-Language

The Relational database management system must be completely manageable through its own extension of SQL. SQL supports data definition View, data manipulation, integrity constraints, authorization and transaction boundary.

View Updating

All views can be updated theoretically, using the RDBMS. It can also be updated by the system itself.

High-Level Update, Insert, Delete

Relational database management system supports inserting, updating, deleting the data as a relational set. A database cannot be called relational, if it uses a single record. At times, it is a procedural technique, when it comes to manipulate the data.

Physical Data Independence

In RDBMS, user accesses the database, via physically like monitors or Application programs must remain logically consistent, when changes to the storages representation or access method to change the data.
Programmers may not check for the primary key uniqueness in his application, because he knows it is enforced by a unique index.

Logical Data Independence

In RDBMS, data changes such as adding, deleting columns or changing field length in a base table.
This rule allows many types of database design changes to be made dynamically, without the user being aware of them.

The Distribution Rule

A Relational Database Management System must have distribution independence. It is one of the most attractive aspects of the RDBMS.

Non-Subversion

If RDBMS supports a low level language, that permits for example, row at a time processing, then this language must not be able to bypass any integrity rules or constraints of the relational language. This is necessary for the data integrity.

Integrity Rule
In RDBMS, integrity constraints specific to a particular relational database must be definable in the relational data sub-languages and storable in the catalogue, not in the Application programs.

Summary
In this article, you learnt about CODD’s Rules in Oracle.