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What are the Codd’s Rules?

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These guidelines can be applied on information source program that manages saved information using only its relational abilities.

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What are the Codd’s


What are the Codd’s Rules?

These guidelines can be applied on information source program that manages

saved information using only its relational abilities. This is a basis concept,

which acts as a base for all the other guidelines.

Rule 1: Information Rule

The information saved in a knowledge base, may it be customer information or

meta-data, must be a value of some desk cell. Everything in a knowledge base

must be saved in a desk format.

Rule 2: Assured Accessibility Rule

Every individual information element (value) is going to be accessible rationally

with a combination of table-name, primary-key (row value), and attribute-name

(column value). No other indicates, such as pointers, can be used to get access


Rule 3: Methodical Therapy of NULL Values

The NULL principles in a knowledge source must be given a thorough and

uniform treatment. This is a very important concept because a NULL can be

considered as one the following − information is missing, information is not

known, or information is not applicable.

Rule 4: Active On the internet Catalog

The framework description of the entire information source must be saved in an

internet based collection, known as information vocabulary, which can be

utilized by authorized customers. Users can use the same query terminology to

connect to the collection which they use to connect to the information source


Rule 5: Comprehensive Data Sub-Language Rule

A data base can only be utilized using a terminology having straight line format

that supports information definition, information adjustment, and transaction

management functions. This terminology can be used directly or through some

program. If the information source allows access information without any help

of this terminology, then it is considered as a violation.

Rule 6: Perspective Upgrading Rule

All the views of a knowledge source, which can hypothetically be updated,

must also be updatable by the program.

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

An information source must assistance high-level placement, updation, and

removal. This must not be limited to a individual row, that is, it must also

assistance union, junction and less functions to generate sets of information


Rule 8: Actual Data Independence

The information saved in a knowledge source must be in addition to the

programs that connect to the information source. Any alternation in the

physique of a knowledge source must not have any effect on how the

information is being utilized by external programs.

Rule 9: Sensible Data Independence

The logical information in a knowledge source must be separate of its user’s

view (application). Any alternation in logical information must not affect the

programs using it. For example, if two platforms are combined or one is split

into two different platforms, there should be no effect or modify on the

consumer program. This is one of the most difficult concept to apply.

Rule 10: Reliability Independence

An information source must be in addition to the program that uses it. All its

integrity restrictions can be individually customized without the need of any

alternation in the program. This concept makes a knowledge source in addition

to the front-end program and its customer interface.

Rule 11: Submission Independence

The end-user must not be able to see that the information is allocated over

various locations. Users should always get the impression that the information

is located at one site only. This concept has been regarded as the basis of

allocated information source systems.

Rule 12: Non-Subversion Rule

If a program has an customer interface that provides access low-level

information, then the consumer interface must not be able to subvert the

program and bypass security and integrity restrictions. You can join the dba

institute with the oracle course to make your career in this field.